Semiconductor Device, Input/Output Device, and Electronic Appliance

ABSTRACT

A flexible input/output device and an input/output device having high resistance to repeated bending are provided. The input/output device includes a first flexible substrate, a first insulating layer over the first substrate, a first transistor over the first insulating layer, a light-emitting element over and electrically connected to the first transistor and including an EL layer between first and second electrodes, a first bonding layer over the light-emitting element, a sensing element and a second transistor over the first bonding layer and electrically connected to each other, a second insulating layer over the sensing element and the second transistor, and a second flexible substrate over the second insulating layer. In the input/output device, B/A is greater than or equal to 0.7 and less than or equal to 1.7, where A is a thickness between the EL layer and the first insulating layer and B is a thickness between the EL layer and the second insulating layer.

BACKGROUND OF THE INVENTION

This application is a continuation of copending U.S. application Ser.No. 14/700,527, filed on Apr. 30, 2015 which is incorporated herein byreference.

1. FIELD OF THE INVENTION

One embodiment of the present invention relates to an input/outputdevice, and particularly to a flexible input/output device.

Note that one embodiment of the present invention is not limited to theabove technical field. One embodiment of the invention disclosed in thisspecification and the like relates to an object, a method, or amanufacturing method. One embodiment of the present invention relates toa process, a machine, manufacture, or a composition of matter.Specifically, examples of the technical field of one embodiment of thepresent invention disclosed in this specification include asemiconductor device, a display device, a light-emitting device, a powerstorage device, a memory device, an electronic appliance, a lightingdevice, an input device (e.g., a touch sensor), an output device, aninput/output device (e.g., a touch panel), a method for driving any ofthem, and a method for manufacturing any of them.

In this specification and the like, a semiconductor device generallymeans a device that can function by utilizing semiconductorcharacteristics. A semiconductor element such as a transistor, asemiconductor circuit, an arithmetic device, and a memory device areeach an embodiment of a semiconductor device. An imaging device, adisplay device, a liquid crystal display device, a light-emittingdevice, an electro-optical device, a power generation device (includinga thin-film solar cell and an organic thin-film solar cell), and anelectronic appliance may each include a semiconductor device.

2. DESCRIPTION OF THE RELATED ART

Light-emitting elements utilizing electroluminescence (EL) (suchelements are also referred to as EL elements) have features of the easeof being thinner and lighter, high speed response to input signals, andcapability of DC low voltage driving and have been expected to beapplied to display devices and lighting devices.

Furthermore, a flexible device in which a functional element such as asemiconductor element, a display element, or a light-emitting element isprovided over a substrate having flexibility (hereinafter also referredto as flexible substrate) has been developed. Typical examples of theflexible device include a lighting device, an image display device, anda variety of semiconductor circuits including a semiconductor elementsuch as a transistor.

Patent Document 1 discloses a flexible active matrix light-emittingdevice in which an organic EL element and a transistor serving as aswitching element are provided over a film substrate.

Display devices are expected to be applied to a variety of uses andbecome diversified. For example, a smartphone and a tablet with a touchpanel are being developed as portable information terminals.

REFERENCE

Patent Document 1: Japanese Published Patent Application No. 2003-174153

SUMMARY OF THE INVENTION

What is desirable is a flexible touch panel in which a flexible displaypanel is provided with a function of inputting data with a finger or thelike touching a screen as a user interface.

An object of one embodiment of the present invention is to provide aflexible input/output device. Another object of one embodiment of thepresent invention is to provide a lightweight input/output device.Another object of one embodiment of the present invention is to providea thin input/output device. Another object of one embodiment of thepresent invention is to provide an input/output device with highdetection sensitivity. Another object of one embodiment of the presentinvention is to achieve both a reduction in thickness and high detectionsensitivity of an input/output device. Another object of one embodimentof the present invention is to provide a large-sized input/outputdevice.

Another object of one embodiment of the present invention is tomanufacture an input/output device through a small number of steps.Another object of one embodiment of the present invention is tomanufacture an input/output device with high yield.

Another object of one embodiment of the present invention is to providea highly reliable input/output device. Another object of one embodimentof the present invention is to provide an input/output device with highresistance to repeated bending. Another object of one embodiment of thepresent invention is to provide a novel semiconductor device, a novellight-emitting device, a novel display device, a novel input/outputdevice, a novel electronic appliance, or a novel lighting device.

Note that the descriptions of these objects do not disturb the existenceof other objects. In one embodiment of the present invention, there isno need to achieve all the objects. Other objects will be apparent fromand can be derived from the description of the specification, thedrawings, the claims, and the like.

One embodiment of the present invention is an input/output device thatincludes a first flexible substrate, a first insulating layer over thefirst substrate, a first transistor over the first insulating layer, alight-emitting element over the first transistor, a first bonding layerover the light-emitting element, a sensing element and a secondtransistor over the first bonding layer, a second insulating layer overthe sensing element and the second transistor, and a second flexiblesubstrate over the second insulating layer. The light-emitting elementincludes a first electrode, a second electrode, and a layer containing alight-emitting organic compound (also referred to as an EL layer)between the first electrode and the second electrode, and emits lighttoward the second substrate. The first transistor and the light-emittingelement are electrically connected to each other. The second transistorand the sensing element are electrically connected to each other. In alight-emitting region of a pixel, B/A is greater than or equal to 0.7and less than or equal to 1.7, where A is a thickness between the ELlayer and the first insulating layer and B is a thickness between the ELlayer and the second insulating layer.

Note that in this specification and the like, the expression “ComponentY over Component X” is not limited to the case where Component X andComponent Y overlap each other. Component X and Component Y may notoverlap each other, or Component X and Component Y may at least partlyoverlap each other.

One embodiment of the present invention is an input/output device thatincludes a first flexible substrate, a first insulating layer over thefirst substrate, a first transistor over the first insulating layer, alight-emitting element over the first transistor, a first bonding layerover the light-emitting element, a sensing element and a secondtransistor over the first bonding layer, a second insulating layer overthe sensing element and the second transistor, and a second flexiblesubstrate over the second insulating layer. The light-emitting elementincludes a first electrode, a second electrode, and a first layer. Thefirst layer contains a light-emitting organic compound and is positionedbetween the first electrode and the second electrode. The light-emittingelement has a function of emitting light toward the second substrate.The first transistor and the light-emitting element are electricallyconnected to each other. The second transistor and the sensing elementare electrically connected to each other. A light-emitting region of apixel includes a region where a thickness between the first layer andthe first insulating layer is A and a region where a thickness betweenthe first layer and the second insulating layer is B, and B/A is greaterthan or equal to 0.7 and less than or equal to 1.7.

The thickness of the input/output device with each of theabove-described structures is preferably greater than or equal to 10 μmand less than or equal to 100 μm. Alternatively, for example, theinput/output device of one embodiment of the present inventionpreferably includes a region with a thickness of greater than or equalto 10 μm and less than or equal to 100 μm.

In each of the above-described structures, the thickness of the firstbonding layer is preferably greater than or equal to 50 nm and less thanor equal to 10 μm. Alternatively, for example, the first bonding layerin the input/output device of one embodiment of the present inventionpreferably includes a region with a thickness of greater than or equalto 50 nm and less than or equal to 10 μm.

In each of the above-described structures, a first conductive layer ispreferably provided over the first insulating layer; the sensing elementpreferably includes a pair of electrodes and a third insulating layerbetween the pair of electrodes; and one of the pair of electrodes andthe first conductive layer are preferably electrically connected to eachother through a conductive connector.

In each of the above-described structures, a second bonding layer ispreferably provided between the first substrate and the first insulatinglayer, and the thickness of the second bonding layer is preferablygreater than or equal to 50 nm and less than or equal to 10 μm.Alternatively, for example, the second bonding layer in the input/outputdevice of one embodiment of the present invention preferably includes aregion with a thickness of greater than or equal to 50 nm and less thanor equal to 10 μm.

In each of the above-described structures, a third bonding layer ispreferably provided between the second substrate and the secondinsulating layer, and the thickness of the third bonding layer ispreferably greater than or equal to 50 nm and less than or equal to 10μm. Alternatively, for example, the third bonding layer in theinput/output device of one embodiment of the present inventionpreferably includes a region with a thickness of greater than or equalto 50 nm and less than or equal to 10 μm.

In each of the above-described structures, a fourth frame-like bondinglayer that surrounds the first bonding layer is preferably provided.

In each of the above-described structures, at least part of an edge ofthe second bonding layer is preferably positioned outside an edge of thefirst substrate.

In each of the above-described structures, at least part of an edge ofthe third bonding layer is preferably positioned outside an edge of thesecond substrate.

Note that the input/output device of one embodiment of the presentinvention in this specification and the like may include, in itscategory, modules such as a module provided with a connector such as aflexible printed circuit (FPC) or a tape carrier package (TCP) and amodule directly mounted with an integrated circuit (IC) by a chip onglass (COG) method or the like. Alternatively, these modules mayinclude, in its category, the input/output device of one embodiment ofthe present invention.

According to one embodiment of the present invention, a flexibleinput/output device can be provided. According to one embodiment of thepresent invention, a lightweight input/output device can be provided.According to one embodiment of the present invention, a thininput/output device can be provided. According to one embodiment of thepresent invention, an input/output device with high detectionsensitivity can be provided. According to one embodiment of the presentinvention, both a reduction in thickness and high detection sensitivityof an input/output device can be achieved. According to one embodimentof the present invention, a large-sized input/output device can beprovided.

According to one embodiment of the present invention, an input/outputdevice can be manufactured through a small number of steps. According toone embodiment of the present invention, an input/output device can bemanufactured with high yield.

According to one embodiment of the present invention, a highly reliableinput/output device can be provided. According to one embodiment of thepresent invention, an input/output device with high resistance torepeated bending can be provided. According to one embodiment of thepresent invention, a novel semiconductor device, a novel light-emittingdevice, a novel display device, a novel input/output device, a novelelectronic appliance, or a novel lighting device can be provided.

Note that the description of these effects does not disturb theexistence of other effects. One embodiment of the present invention doesnot necessarily have all the effects. Other effects will be apparentfrom and can be derived from the description of the specification, thedrawings, the claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B each illustrate an example of an input/output device.

FIG. 2 illustrates an example of an input/output device.

FIGS. 3A to 3C each illustrate an example of an input/output device.

FIGS. 4A to 4D illustrate an example of an input/output device.

FIGS. 5A and 5B illustrate an example of an input/output device.

FIGS. 6A to 6C each illustrate an example of an input/output device.

FIG. 7 illustrates an example of an input/output device.

FIG. 8 illustrates an example of an input/output device.

FIGS. 9A and 9B illustrate an example of an input/output device.

FIGS. 10A, 10B, 10C1, and 10C2 illustrate examples of structures of aninput device, a sensing unit, and a converter and an example of a methodfor driving the sensing unit.

FIGS. 11A to 11C illustrate examples of structures of an input device, asensing unit, and a converter and an example of a method for driving thesensing unit.

FIGS. 12A to 12D illustrate an example of a method for manufacturing aninput/output device.

FIGS. 13A to 13D illustrate an example of a method for manufacturing aninput/output device.

FIGS. 14A to 14D illustrate an example of a method for manufacturing aninput/output device.

FIGS. 15A to 15C each illustrate an example of a method formanufacturing an input/output device.

FIGS. 16A to 16G illustrate examples of electronic appliances andlighting devices.

FIGS. 17A to 17I illustrate examples of electronic appliances.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments will be described in detail with reference to theaccompanying drawings. Note that the present invention is not limited tothe description below, and it is easily understood by those skilled inthe art that various changes and modifications can be made withoutdeparting from the spirit and scope of the present invention.

Therefore, the invention should not be construed as being limited to thedescription in the following embodiments.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. In some cases, the same hatching pattern isused for portions having similar functions, and the portions are notdenoted by reference numerals.

The position, size, range, or the like of each structure illustrated indrawings and the like is not accurately represented in some cases foreasy understanding. Therefore, the disclosed invention is notnecessarily limited to the position, size, range, or the like disclosedin the drawings and the like.

Note that the terms “film” and “layer” can be interchanged with eachother depending on circumstances or situations. For example, in somecases, the term “conductive film” can be used instead of the term“conductive layer”, and the term “insulating layer” can be used insteadof the term “insulating film”.

Embodiment 1

In this embodiment, an input/output device of one embodiment of thepresent invention is described.

The input/output device of one embodiment of the present inventionincludes a display portion and an input portion. Although the case wherean organic EL element is used in the display portion and a capacitivetouch sensor is used in the input portion is described, one embodimentof the present invention is not limited thereto. A light-emittingelement other than the organic EL element or a display element may beused in the display portion. A sensing element other than a capacitormay be used in the input portion.

Examples of the capacitive touch sensor are a surface capacitive touchsensor and a projected capacitive touch sensor. Examples of theprojected capacitive touch sensor are a self-capacitive touch sensor anda mutual capacitive touch sensor. The use of a mutual capacitive type ispreferable because multiple points can be sensed simultaneously.

FIG. 1A is a schematic cross-sectional view of an input/output device ofone embodiment of the present invention. The input/output deviceillustrated in FIG. 1A includes a first flexible substrate 101, a firstinsulating layer 103 over the first substrate 101, a first transistor105 over the first insulating layer 103, a light-emitting element 107over the first transistor 105, a first bonding layer 109 over thelight-emitting element 107, a sensing element and a second transistor,which are collectively illustrated as an element layer 111, over thefirst bonding layer 109, a second insulating layer 113 over the sensingelement and the second transistor, and a second flexible substrate 115over the second insulating layer 113. The light-emitting element 107includes a first electrode 107 a, a second electrode 107 c, and an ELlayer 107 b between the first electrode 107 a and the second electrode107 c. The light-emitting element 107 emits light toward the secondsubstrate 115. The first transistor 105 and the light-emitting element107 are electrically connected to each other. The second transistor andthe sensing element are electrically connected to each other. In alight-emitting region of a pixel, B/A is greater than or equal to 0.7and less than or equal to 1.7, where A is a thickness between the ELlayer 107 b and the first insulating layer 103 and B is a thicknessbetween the EL layer 107 b and the second insulating layer 113. Here,the thickness A does not include the thicknesses of the EL layer 107 band the first insulating layer 103. Similarly, the thickness B does notinclude the thicknesses of the EL layer 107 b and the second insulatinglayer 113.

Since the light-emitting element and the sensing element are providedbetween the pair of flexible substrates in one embodiment of the presentinvention, a flexible input/output device can be achieved. In addition,the weight and thickness of the input/output device can be reduced.

In the laminated structure included in the input/output device, theadhesion especially between the EL layer and the electrode is low or theadhesion between layers included in the EL layer is low in some cases.In such a case, the EL layer is partly separated when the flexibleinput/output device is bent, resulting in poor light emission.

In the light-emitting region of the pixel in the input/output device ofone embodiment of the present invention, B/A is greater than or equal to0.7 and less than or equal to 1.7, where A is a thickness between the ELlayer and the first insulating layer and B is a thickness between the ELlayer and the second insulating layer. With such a structure, a neutralplane where distortion due to stress such as compressive stress ortensile stress against deformation such as bending does not occur (aplane that does not expand or contract) is positioned in the EL layer ornear the EL layer. Thus, separation of the EL layer due to bending orthe like can be inhibited, so that the input/output device can be highlyreliable. Moreover, the input/output device can have high resistance torepeated bending.

In terms of reduction in thickness and weight, improvement inflexibility, or the like, the thickness of the input/output device ofone embodiment of the present invention is, for example, preferably lessthan or equal to 1 mm, further preferably less than or equal to 500 μm,still further preferably less than or equal to 300 μm, particularlypreferably less than or equal to 100 μm. In addition, in terms ofmechanical strength or the like, the thickness of the input/outputdevice of one embodiment of the present invention is, for example,preferably greater than or equal to 1 μm, further preferably greaterthan or equal to 5 μm, still further preferably greater than or equal to10 μm. The thickness of the input/output device of one embodiment of thepresent invention is, for example, preferably greater than or equal to10 μm and less than or equal to 100 μm. This can inhibit breakage of theelement or the like due to stress in bending, so that the input/outputdevice can have high resistance to repeated bending.

Furthermore, in terms of reduction in thickness and weight, improvementin flexibility, or the like, the thickness of the first bonding layeris, for example, preferably greater than or equal to 50 nm and less thanor equal to 10 μm, further preferably greater than or equal to 50 nm andless than or equal to 5 μm, still further preferably greater than orequal to 50 nm and less than or equal to 3 μm.

In one embodiment of the present invention, the light-emitting element,a color filter, and a microresonator (a microcavity structure) arepreferably combined in order to maintain high color reproducibility orto extract light with high color purity and achieve high-definitiondisplay. By providing the color filter so as to overlap with thelight-emitting element, the color purity of light from a pixel can beincreased. In addition, by providing a light-blocking layer between twoadjacent color filters, mixture of light emitted from two adjacentpixels can be inhibited, resulting in high display quality.

When a viewer looks at display of the input/output device having themicrocavity structure and the viewer's eyes are perpendicular to a panelplane, the viewer can recognize high-intensity light of a desired color.On the other hand, as the viewer's eyes deviate from the positionperpendicular to the display plane, it becomes more difficult for theviewer to recognize light of the desired color. Furthermore, as thedistance from the light-emitting element to the color filter increases,the viewing angle dependence increases. Thus, in the case where thefirst bonding layer is provided between the light-emitting element andthe color filter, the thickness of the first bonding layer is preferablysmall and preferably falls within any of the above-described ranges alsoin terms of reduction in viewing angle dependence.

The first substrate and the second substrate preferably have the samethickness or substantially the same thickness. When the first substrateand the second substrate have the same thickness, the transistor and thesensing element as well as the light-emitting element can be positionedin the central part of the input/output device. As a result, breakage ofthe element or the like due to stress in bending can be inhibited, sothat the input/output device can have high resistance to repeatedbending. The ratio of the thickness of the second substrate to thethickness of the first substrate is, for example, less than or equal to±20%, preferably less than or equal to ±10%, further preferably lessthan or equal to ±5%.

In terms of reduction in thickness and weight, improvement inflexibility, or the like, the thickness of each of the first substrateand the second substrate is, for example, preferably less than or equalto 500 μm, further preferably less than or equal to 200 μm, stillfurther preferably less than or equal to 100 μm, still furtherpreferably less than or equal to 50 μm, particularly preferably lessthan or equal to 25 μm. In addition, in terms of mechanical strength orthe like, the thickness of each of the first substrate and the secondsubstrate is, for example, preferably greater than or equal to 1 μm,further preferably greater than or equal to 5 μm, still furtherpreferably less than or equal to 10 μm. The thickness of each of thefirst substrate and the second substrate is, for example, preferablygreater than or equal to 10 μm and less than or equal to 50 μm. This caninhibit breakage of the element or the like due to stress in bending, sothat the input/output device can have high resistance to repeatedbending.

The linear thermal expansion coefficients of materials for the firstsubstrate and the second substrate are preferably the same orsubstantially the same. When the materials have the same linear thermalexpansion coefficient, unintentional curve or curl of the input/outputdevice can be inhibited even when heat in a manufacturing process ortemperature in use of the device is changed. In addition, the range ofguaranteed operating temperature can be expanded. The difference betweenthe linear thermal expansion coefficient of the material for the firstsubstrate and that of the material for the second substrate attemperatures, for example, from 0° C. to 200° C. is preferably 10 μm/Kor less, further preferably 5 μm/K or less, still further preferably 2μm/K or less.

FIG. 1B is a schematic cross-sectional view of an input/output device ofone embodiment of the present invention. The input/output deviceillustrated in FIG. 1B differs from the input/output device illustratedin FIG. 1A in that a second bonding layer 102 is provided between thefirst substrate 101 and the first insulating layer 103 and that a thirdbonding layer 114 is provided between the second substrate 115 and thesecond insulating layer 113.

A layer to be separated can be formed over a formation substrate,separated from the formation substrate, and then transferred to anothersubstrate. With this method, for example, a layer to be separated thatis formed over a formation substrate having high heat resistance can betransferred to a substrate having low heat resistance. Thus, theformation temperature of the layer to be separated is not limited by thesubstrate having low heat resistance. Moreover, the layer to beseparated can be transferred to a substrate or the like that is morelightweight or flexible or thinner than the formation substrate, wherebyreduction in thickness and weight and improvement in flexibility of theinput/output device can be achieved.

The input/output device of one embodiment of the present invention canbe manufactured as described below, for example. First, the firstinsulating layer, the first transistor, the light-emitting element, andthe like are formed over a first formation substrate. In addition, thesecond insulating layer, the second transistor, the sensing element, andthe like are formed over a second formation substrate. Then, the pair offormation substrates are attached to each other with the first bondinglayer. After that, the first formation substrate is separated, and thefirst substrate and the first insulating layer are attached to eachother with the second bonding layer. In addition, the second formationsubstrate is separated, and the second substrate and the secondinsulating layer are attached to each other with the third bondinglayer.

A transistor and the like are formed over a formation substrate havinghigh heat resistance, whereby a highly reliable transistor and aninsulating film with a sufficiently high moisture-resistant property canbe formed at high temperature. Then, the transistor and the insulatingfilm are transferred to a substrate having low heat resistance, wherebya highly reliable input/output device can be manufactured. Thus, in oneembodiment of the present invention, a thin or lightweight input/outputdevice with high reliability can be provided.

In terms of reduction in thickness and weight, improvement inflexibility, or the like, the thickness of each of the second bondinglayer and the third bonding layer is preferably greater than or equal to50 nm and less than or equal to 10 μm, further preferably greater thanor equal to 50 nm and less than or equal to 5 μm, still furtherpreferably greater than or equal to 50 nm and less than or equal to 3μm.

The input/output device of one embodiment of the present invention has astructure in which the substrate supporting the sensing element and thesubstrate supporting the light-emitting element are positioned facingeach other. In addition, an active matrix touch sensor including both acapacitor that is a sensing element and an active element such as atransistor is used. This structure allows the touch sensor to be lesslikely to be affected by noise caused when the light-emitting element isdriven. Thus, a reduction in detection sensitivity can be inhibited evenwhen the touch sensor and the light-emitting element are interposedbetween the two substrates and positioned close to each other.

The input/output device of one embodiment of the present invention isdescribed in detail below.

FIG. 2 is a projection view illustrating a structure of an input/outputdevice 500TP. Note that part of a sensing unit 602 and part of a pixel502 are enlarged for convenience of explanation.

FIG. 3A is a cross-sectional view illustrating a structure of theinput/output device 500TP taken along Z1-Z2 in FIG. 2. FIGS. 3B and 3Care cross-sectional views each illustrating an example in which thestructure illustrated in FIG. 3A is partly changed.

<Structure Example of Input/Output Device>

As illustrated in FIG. 2, the input/output device 500TP includes adisplay portion 500 and an input portion 600 that overlap each other.

The input portion 600 includes a plurality of sensing units 602 arrangedin a matrix.

The input portion 600 also includes a selection signal line G1, acontrol line RES, and the like to which the plurality of sensing units602 that are arranged in the row direction (indicated by the arrow R inthe drawing) are electrically connected.

The input portion 600 also includes a signal line DL or the like towhich the plurality of sensing units 602 that are arranged in the columndirection (indicated by the arrow C in the drawing) are electricallyconnected.

The sensing unit 602 includes a sensing circuit. The sensing circuit iselectrically connected to the selection signal line G1, the control lineRES, the signal line DL, and the like.

A transistor, a sensing element, and/or the like can be used for thesensing circuit. For example, a conductive film and a capacitorelectrically connected to the conductive film can be used for thesensing circuit. In addition, a capacitor and a transistor electricallyconnected to the capacitor can be used for the sensing circuit.

For the sensing circuit, for example, a capacitor 650 that includes aninsulating layer 653 and a first electrode 651 and a second electrode652 between which the insulating layer 653 is interposed can be used(see FIG. 3A).

The sensing unit includes a plurality of window portions 667 arranged ina matrix. The window portion 667 transmits visible light, and alight-blocking layer BM may be provided between the plurality of windowportions 667.

A coloring layer is provided in a position overlapping with the windowportion 667. The coloring layer transmits light of a predeterminedcolor. Note that the coloring layer can be called a color filter. Forexample, a coloring layer CFB transmitting blue light, a coloring layerCFG transmitting green light, and a coloring layer CFR transmitting redlight can be used. A coloring layer transmitting yellow light or acoloring layer transmitting white light may also be used.

The display portion 500 includes the plurality of pixels 502 arranged ina matrix. The pixel 502 is positioned so as to overlap with the windowportions 667 of the input portion 600.

The pixels 502 may be arranged at higher density than the sensing units602.

The input/output device 500TP described in this embodiment includes theinput portion 600 that includes the plurality of sensing units 602arranged in a matrix and provided with the window portions 667transmitting visible light, the display portion 500 that includes theplurality of pixels 502 overlapping with the window portions 667, andthe coloring layers between the window portions 667 and the pixels 502.In addition, each sensing unit is provided with a switch with whichinterference with another sensing unit can be reduced.

With such a structure, sensing data sensed by each sensing unit can besupplied together with the positional data of the sensing unit. Inaddition, the sensing data associated with the positional data of thepixel for displaying an image can be supplied. Electrical continuitybetween a sensing unit that does not supply sensing data and the signalline is not established, whereby interference with a sensing unit thatsupplies a sensing signal can be reduced. Consequently, the novelinput/output device 500TP that is highly convenient or highly reliablecan be provided.

For example, the input portion 600 of the input/output device 500TP cansense sensing data and supply the sensing data together with thepositional data. Specifically, a user of the input/output device 500TPcan make a variety of gestures (e.g., tap, drag, swipe, and pinch-inoperation) using, as a pointer, his/her finger or the like on the inputportion 600.

The input portion 600 can sense a finger or the like that approaches ortouches the input portion 600 and supply sensing data including thesensed position, track, or the like.

An arithmetic unit determines whether or not supplied data satisfies apredetermined condition on the basis of a program or the like andexecutes an instruction associated with a predetermined gesture.

Thus, a user of the input portion 600 can make the predetermined gesturewith his/her finger and make the arithmetic unit execute an instructionassociated with the predetermined gesture.

For example, first, the input portion 600 of the input/output device500TP selects one sensing unit X from the plurality of sensing unitsthat can supply sensing data to one signal line. Then, electricalcontinuity between the sensing units other than the sensing unit X andthe signal line is not established. This can reduce interference of theother sensing units with the sensing unit X.

Specifically, interference of sensing elements of the other sensingunits with a sensing element of the sensing unit X can be reduced.

For example, in the case where a capacitor and a conductive film towhich one electrode of the capacitor is electrically connected are usedfor the sensing element, interference of the potentials of theconductive films of the other sensing units with the potential of theconductive film of the sensing unit X can be reduced.

Thus, the input/output device 500TP can drive the sensing unit andsupply sensing data independently of its size. The input/output device500TP can have a variety of sizes, for example, ranging from a size fora hand-held device to a size for an electronic blackboard.

The input/output device 500TP can be folded and unfolded. Even in thecase where interference of the other sensing units with the sensing unitX is different between the folded state and the unfolded state, thesensing unit can be driven and sensing data can be supplied withoutdependence on the state of the input/output device 500TP.

The display portion 500 of the input/output device 500TP can be suppliedwith display data. For example, the arithmetic unit can supply thedisplay data.

In addition to the above structure, the input/output device 500TP canhave the following structure.

The input portion 600 of the input/output device 500TP may include adriver circuit 603 g or a driver circuit 603 d. In addition, theinput/output device 500TP may be electrically connected to an FPC1.

The display portion 500 of the input/output device 500TP may include ascan line driver circuit 503 g, a signal line driver circuit 503 s, awiring 511, and a terminal 519. In addition, the display portion 500 maybe electrically connected to an FPC2.

In addition, a protective layer 670 that prevents damage and protectsthe input/output device 500TP may be provided. For example, a ceramiccoat layer or a hard coat layer can be used as the protective layer 670.Specifically, a layer containing aluminum oxide or an ultravioletcurable resin can be used. In addition, an anti-reflection layer 670 pthat weakens the intensity of external light reflected by theinput/output device 500TP can be used. Specifically, a circularlypolarizing plate or the like can be used.

Individual components included in the input/output device 500TP aredescribed below. Note that these components cannot be clearlydistinguished and one component also serves as another component orinclude part of another component in some cases.

For example, the input portion 600 provided with the coloring layers inpositions overlapping with the plurality of window portions 667 alsoserves as a color filter.

Furthermore, for example, the input/output device 500TP in which theinput portion 600 overlaps with the display portion 500 serves as theinput portion 600 and the display portion 500. Note that theinput/output device 500TP in which the input portion 600 overlaps withthe display portion 500 is also referred to as a touch panel.

The input portion 600 includes the sensing unit 602, the selectionsignal line G1, the signal line DL, and the second substrate 115.

The sensing unit 602 senses an object that approaches or touches thesensing unit 602 and supplies a sensing signal. For example, the sensingunit 602 senses, for example, capacitance, illuminance, magnetic force,electric waves, or pressure and supplies data based on the sensedphysical quantity. Specifically, a capacitor, a photoelectric conversionelement, a magnetic sensing element, a piezoelectric element, aresonator, or the like can be used as the sensing element.

The sensing unit 602 senses, for example, a change in capacitancebetween the sensing unit 602 and an object that approaches or touchesthe sensing unit 602. Specifically, a conductive film and a sensingcircuit electrically connected to the conductive film may be used.

Note that when an object having a dielectric constant higher than thatof the air, such as a finger, comes close to a conductive film in theair, the capacitance between the finger and the conductive film changes.The sensing unit 602 can sense the capacitance change and supply sensingdata. Specifically, a conductive film and a sensing circuit including acapacitor one electrode of which is connected to the conductive film canbe used for the sensing unit 602.

For example, the capacitance change causes charge distribution, leadingto voltage change across the capacitor. This voltage change can be usedfor a sensing signal. Specifically, the voltage between the electrodesof the capacitor 650 changes when an object comes close to theconductive film that is electrically connected to one electrode of thecapacitor 650 (see FIG. 3A).

The sensing unit 602 includes a switch that can be turned on or off inaccordance with a control signal. For example, a transistor M12 can beused as the switch.

In addition, a transistor that amplifies a sensing signal can be usedfor the sensing unit 602.

Transistors that can be manufactured through the same process can beused as the transistor that amplifies a sensing signal and the switch.This allows the input portion 600 to be manufactured through asimplified process.

The input portion 600 includes the selection signal line G1, the controlline RES, the signal line DL, and the like. Each line can be formedusing, for example, a conductive material such as an inorganicconductive material, an organic conductive material, a metal, orconductive ceramics.

The driver circuit 603 g can supply selection signals at predeterminedtimings, for example. Specifically, the driver circuit 603 g suppliesselection signals to the selection signal lines G1 row by row in apredetermined order. Any of a variety of circuits can be used as thedriver circuit 603 g. For example, a shift register, a flip-flopcircuit, a combination circuit, or the like can be used.

The driver circuit 603 d supplies sensing data on the basis of a sensingsignal supplied from the sensing unit 602. Any of a variety of circuitscan be used as the driver circuit 603 d. For example, a circuit that canform a source follower circuit or a current mirror circuit by beingelectrically connected to the sensing circuit in the sensing unit can beused as the driver circuit 603 d. In addition, an analog-to-digitalconverter circuit that converts a sensing signal into a digital signalmay be provided in the driver circuit 603 d.

The FPC1 supplies a timing signal, a power supply potential, or the likeand is supplied with a sensing signal.

The display portion 500 includes the pixels 502, the scan lines, thesignal lines, and the first substrate 101 (see FIG. 2).

The pixel 502 includes a sub-pixel 502B, a sub-pixel 502G, and asub-pixel 502R, and each sub-pixel includes a display element and apixel circuit for driving the display element.

The pixel circuit includes, for example, a transistor 502 t.

The display portion 500 includes an insulating film 521 that covers thetransistor 502 t. The insulating film 521 can be used as a layer forplanarizing unevenness caused by the pixel circuits. A stacked filmincluding a layer that can prevent diffusion of impurities can be usedas the insulating film 521. This can inhibit reduction in thereliability of the transistor 502 t or the like due to diffusion ofimpurities.

For example, organic EL elements that emit light of different colors maybe used as display elements in sub-pixels. Alternatively, organic ELelements that emit white light may be used.

For example, a light-emitting element 550R includes a lower electrode,an upper electrode, and an EL layer between the lower electrode and theupper electrode.

The sub-pixel 502R includes a light-emitting module 580R. The sub-pixel502R includes the light-emitting element 550R and a pixel circuit thatcan supply electric power to the light-emitting element 550R andincludes a transistor 502 t. The light-emitting module 580R includes thelight-emitting element 550R and an optical element (e.g., the coloringlayer CFR).

Note that a microcavity structure can be provided for the light-emittingmodule 580R so that light with a specific wavelength can be efficientlyextracted. Specifically, an EL layer may be provided between a film thatreflects visible light and a film that partly reflects and partlytransmits visible light, which are provided so that light with aspecific wavelength can be efficiently extracted.

The light-emitting module 580R includes the coloring layer CFR on thelight extraction side. The coloring layer transmits light with aspecific wavelength and is, for example, a layer that selectivelytransmits light of red, green, blue, or the like. Note that othersub-pixels may be provided so as to overlap with the window portions,which are not provided with the coloring layers, so that light from thelight-emitting element can be emitted without passing through thecoloring layers.

The coloring layer CFR overlaps with the light-emitting element 550R.Accordingly, part of light emitted from the light-emitting element 550Rpasses through the coloring layer CFR and is emitted to the outside ofthe light-emitting module 580R as indicated by an arrow in FIG. 3A.

The light-blocking layer BM is located so as to surround the coloringlayer (e.g., the coloring layer CFR).

In the case where the first bonding layer 109 is provided on the lightextraction side, the first bonding layer 109 may be in contact with thelight-emitting element 550R and the coloring layer CFR.

The lower electrode is provided over the insulating film 521. Apartition wall 528 provided with an opening overlapping with the lowerelectrode is provided. Note that part of the partition wall 528 overlapswith an end portion of the lower electrode.

The lower electrode, the upper electrode, and the EL layer providedbetween the lower electrode and the upper electrode form thelight-emitting element (e.g., the light-emitting element 550R). Thepixel circuit supplies electric power to the light-emitting element.

In addition, a spacer that controls the gap between the first substrate101 and the second substrate 115 is provided over the partition wall528.

In the case of a transflective liquid crystal display or a reflectiveliquid crystal display, some of or all of pixel electrodes function asreflective electrodes. For example, some or all of pixel electrodes areformed to contain aluminum, silver, or the like.

A memory circuit such as an SRAM can be provided under the reflectiveelectrodes, leading to lower power consumption. A structure suitable foremployed display elements can be selected from among a variety ofstructures of pixel circuits.

The first substrate 101 and the second substrate 115 are attached toeach other with the first bonding layer 109. The first bonding layer 109has a refractive index higher than that of the air.

Note that the pixel circuit or the light-emitting element (e.g., thelight-emitting element 550R) is positioned between the first substrate101 and the second substrate 115.

The scan line driver circuit 503 g supplies a selection signal. Thesignal line driver circuit 503 s supplies an image signal. Asillustrated in FIG. 3A, the signal line driver circuit 503 s includes atransistor 503 t and a capacitor 503 c. Note that transistors used inthe pixel circuit and the driver circuit can be formed through the sameprocess and over the same substrate.

The display portion 500 includes wirings such as scan lines, signallines, and power supply lines. Any of a variety of conductive films canbe used for the wirings.

For example, a conductive film similar to the conductive film that canbe used for the input portion 600 can be used.

The display portion 500 includes a wiring 511 through which a signal canbe supplied. The wiring 511 is provided with a terminal 519. Note thatthe FPC2 through which a signal such as an image signal or asynchronization signal can be supplied is electrically connected to theterminal 519.

Note that a printed wiring board (PWB) may be attached to the FPC2.

<Modification Example of Input/Output Device>

Any of various kinds of transistors can be used in the input portion 600and/or the display portion 500.

FIG. 3A illustrates a structure in which a bottom-gate transistor isused in the input portion 600.

FIGS. 3A and 3B each illustrate a structure in which a bottom-gatetransistor is used in the display portion 500.

For example, a semiconductor layer containing an oxide semiconductor,amorphous silicon, or the like can be used in the transistor 502 t andthe transistor 503 t illustrated in FIG. 3A.

For example, a semiconductor layer containing polycrystalline siliconthat is obtained by crystallization process such as laser annealing canbe used in the transistor 502 t and the transistor 503 t illustrated inFIG. 3B.

FIG. 3C illustrates a structure in which a top-gate transistor is usedin the display portion 500.

For example, a semiconductor layer including a polycrystalline siliconfilm, a single crystal silicon film that is transferred from a singlecrystal silicon substrate, or the like can be used in the transistor 502t and the transistor 503 t illustrated in FIG. 3C.

Specific examples of cross-sectional structures of the input/outputdevice of one embodiment of the present invention are described indetail below.

<Specific Example 1 of Cross-Sectional Structure>

FIG. 4A is an example of a cross-sectional view of the input/outputdevice of one embodiment of the present invention. FIGS. 4B and 4C eachillustrate an example of a structure of a light-emitting element. FIG.4D is an enlarged view of a transistor FET1 and a sensing element C1.

The input/output device illustrated in FIG. 4A includes a substrate 801,a bonding layer 811, an insulating layer 813, a plurality oftransistors, a conductive layer 857 a, an insulating layer 815, aninsulating layer 817 a, an insulating layer 817 b, a conductive layer856, a plurality of light-emitting elements, an insulating layer 821, abonding layer 822, a spacer 823, an overcoat 851, an insulating layer852 a, an insulating layer 852 b, a coloring layer 845, a light-blockinglayer 847, a conductive layer 857 b, a conductive layer 857 c, aplurality of sensing elements, an insulating layer 843, a bonding layer841, and a substrate 803. The bonding layer 822, the overcoat 851, theinsulating layer 852 a, the insulating layer 852 b, the insulating layer843, the bonding layer 841, and the substrate 803 transmit visiblelight.

The substrate 801 corresponds to the first substrate 101 in FIG. 1B. Thebonding layer 811, the insulating layer 813, the bonding layer 822, theinsulating layer 843, the bonding layer 841, and the substrate 803correspond to the second bonding layer 102, the first insulating layer103, the first bonding layer 109, the second insulating layer 113, thethird bonding layer 114, and the second substrate 115, respectively.

In FIG. 4A, light-emitting elements 830, transistors, and sensingelements C1 included in a light-emitting portion 804 and a drivercircuit portion 806 are sealed with the substrate 801, the substrate803, and the bonding layer 822.

The conductive layer 857 a is electrically connected to an externalinput terminal through which a signal or a potential from the outside istransmitted to the driver circuit portion 806. In this example, the FPC2is provided as the external input terminal. To prevent an increase inthe number of manufacturing steps, the conductive layer 857 a ispreferably formed using the same material and steps as those of theelectrode or the wiring in the light-emitting portion or the drivercircuit portion. In this example, the conductive layer 857 a is formedusing the same material and steps as those of the electrode in thetransistor 820. The FPC2 and the conductive layer 857 a are electricallyconnected to each other through a connector 825 a. An FPC1 andconductive layers 857 b and 857 c are electrically connected to eachother through a connector 825 b.

As illustrated in FIG. 4B, the light-emitting element 830 includes afirst electrode 831, an EL layer 833, and a second electrode 835.

As illustrated in FIG. 4C, the light-emitting element in one embodimentof the present invention may include the first electrode 831, an opticaladjustment layer 832, the EL layer 833, and the second electrode 835. Alight-transmitting conductive material is preferably used for theoptical adjustment layer 832.

As illustrated in FIG. 4D, the transistor FET1 includes a gate electrode304 over the insulating layer 843, a gate insulating layer 305 coveringthe gate electrode 304, a semiconductor layer 308 a over the gateinsulating layer 305, and a pair of electrodes (an electrode 310 a andan electrode 310 b). The semiconductor layer 308 a is connected to thepair of electrodes. The pair of electrodes have functions as a sourceelectrode and a drain electrode. The transistor FET1 is covered with aninsulating layer 312 and an insulating layer 314. Either the insulatinglayer 312 or the insulating layer 314 is not necessarily provided. Thesensing element C1 includes a first electrode 11 over the insulatinglayer 314, an insulating layer 852 a over the first electrode 11, and asecond electrode 12 over the insulating layer 852 a. An insulating layer852 b is provided over the second electrode 12, and the light-blockinglayer 847 and the coloring layer 845 are provided over the insulatinglayer 852 b. Although the transistor FET1 overlaps with thelight-blocking layer 847 and the sensing element C1 overlaps with thecoloring layer 845 in this example, one embodiment of the presentinvention is not limited thereto. For example, both the transistor FET1and the sensing element C1 may overlap with the light-blocking layer847. In this case, the sensing element C1 does not necessarily have alight-transmitting property. In the case where the electrode of thesensing element C1 overlaps with the coloring layer 845 or alight-emitting region of the light-emitting element 830, the electrodeis preferably formed using a light-transmitting material.

The first electrode 11 or the second electrode 12 may be formed usingthe same material and steps as those of a back gate of the transistor.Although the transistor included in the driver circuit portion 806includes a back gate in FIG. 4A, one embodiment of the present inventionis not limited thereto.

Note that in the input/output device illustrated in FIG. 4A, a user canrecognize the wiring, the electrode of the transistor FET1, and the likein some cases. Thus, a film with a low reflecting property or alight-blocking film may be provided between the substrate 803 and thetransistor FET1. Alternatively, a conductive film with a low reflectingproperty may be used as the wiring and the electrode of the transistorFET1.

As illustrated in FIG. 4A, in a light-emitting region of a pixel in theinput/output device of one embodiment of the present invention, B/A isgreater than or equal to 0.7 and less than or equal to 1.7, where A is athickness between the EL layer 833 and the insulating layer 813 and B isa thickness between the EL layer 833 and the insulating layer 843. Withsuch a structure, a neutral plane where distortion due to stress such ascompressive stress or tensile stress against deformation such as bendingdoes not occur (a plane that does not expand or contract) is positionedin the EL layer or near the EL layer. Thus, separation of the EL layerdue to bending or the like can be inhibited, so that the input/outputdevice can be highly reliable. Moreover, the input/output device canhave high resistance to repeated bending.

<Specific Example 2 of Cross-Sectional Structure>

FIG. 5A is an example of a cross-sectional view of the input/outputdevice of one embodiment of the present invention. FIG. 5B is anenlarged view of a transistor FET2 and a sensing element C2.

The input/output device illustrated in FIG. 5A differs from theinput/output device illustrated in FIG. 4A in that the transistor FET2and the sensing element C2 are included. The same portions as in theinput/output device illustrated in FIG. 4A are not described here.

As illustrated in FIG. 5B, the transistor FET2 includes the gateelectrode 304 over the insulating layer 843, the gate insulating layer305 covering the gate electrode 304, the semiconductor layer 308 a overthe gate insulating layer 305, and the pair of electrodes 310 a and 310b. The semiconductor layer 308 a is connected to the pair of electrodes310 a and 310 b. The pair of electrodes 310 a and 310 b have functionsas a source electrode and a drain electrode. The transistor FET2 iscovered with the insulating layer 312 and the insulating layer 314.Either the insulating layer 312 or the insulating layer 314 is notnecessarily provided. The sensing element C2 includes the firstelectrode 11 over the gate insulating layer 305, the insulating layer314 and the insulating layer 852 a over the first electrode 11, and thesecond electrode 12 over the insulating layer 852 a. The insulatinglayer 852 b is provided over the second electrode 12, and thelight-blocking layer 847 and the coloring layer 845 are provided overthe insulating layer 852 b. Although the transistor FET2 overlaps withthe light-blocking layer 847 and the sensing element C2 overlaps withthe coloring layer 845 in this example, one embodiment of the presentinvention is not limited thereto. For example, both the transistor FET2and the sensing element C2 may overlap with the light-blocking layer847.

In one embodiment of the present invention, the semiconductor layerincluded in the transistor and the electrode of the sensing element arepreferably formed in the same step. This can reduce the number of stepsfor manufacturing the input/output device, resulting in lowmanufacturing cost.

For example, an oxide semiconductor can be used for the semiconductorlayer of the transistor. An oxide semiconductor layer has a highlight-transmitting property. By increasing oxygen vacancies and/orimpurities such as hydrogen and water in the oxide semiconductor layer,an oxide semiconductor layer having high carrier density and lowresistance (also referred to as an oxide conductor layer) can beobtained. Such an oxide semiconductor layer can be suitably used as anelectrode of a capacitor of a touch sensor.

Specifically, plasma treatment is performed on an island-shaped oxidesemiconductor layer that is to be the first electrode 11 to increaseoxygen vacancies in the oxide semiconductor layer and/or impurities suchas hydrogen and water in the oxide semiconductor layer, so that theoxide semiconductor layer can have high carrier density and lowresistance.

A typical example of the plasma treatment performed on the oxidesemiconductor layer is plasma treatment using a gas containing one of arare gas (He, Ne, Ar, Kr, or Xe), phosphorus, boron, hydrogen, andnitrogen. Specifically, plasma treatment in an Ar atmosphere, plasmatreatment in a mixed gas atmosphere of Ar and hydrogen, plasma treatmentin an ammonia atmosphere, plasma treatment in a mixed gas atmosphere ofAr and ammonia, plasma treatment in a nitrogen atmosphere, or the likecan be employed.

Furthermore, the insulating layer 314 containing hydrogen is formed incontact with the oxide semiconductor layer to diffuse hydrogen from theinsulating layer containing hydrogen to the oxide semiconductor layer,so that the oxide semiconductor layer can have higher carrier densityand lower resistance. An example of the insulating film containinghydrogen, that is, an insulating film capable of releasing hydrogen is asilicon nitride film.

The insulating layer 312 is provided over the transistor FET2 in orderto prevent the semiconductor layer 308 a from being subjected to theplasma treatment. Since the insulating layer 312 is provided, thesemiconductor layer 308 a is not in contact with the insulating layer314 containing hydrogen. By forming the insulating layer 312 using aninsulating film capable of releasing oxygen, oxygen can be supplied tothe semiconductor layer 308 a. The semiconductor layer 308 a to whichoxygen is supplied is an oxide semiconductor in which oxygen vacanciesin the film or at the interface are reduced and which has highresistance. Note that as the insulating film capable of releasingoxygen, for example, a silicon oxide film or a silicon oxynitride filmcan be used.

FIG. 6A is a schematic cross-sectional view illustrating an input/outputdevice including four sub-pixels. A color filter method is employed inthe input/output device of one embodiment of the present invention. Thelight-emitting element 830 illustrated in FIG. 6A has a structuresimilar to the structure illustrated in FIG. 4C and includes the firstelectrode 831, the optical adjustment layer 832, the EL layer 833, andthe second electrode 835 in this order. The combination of a microcavitystructure (optical adjustment layer) and a red coloring layer CFR, agreen coloring layer CFG, a blue coloring layer CFB, and a yellowcoloring layer CFY allows light with high color purity to be extractedfrom the input/output device of one embodiment of the present invention.The thickness of the optical adjustment layer may be varied depending onthe color of the sub-pixel. Note that although FIG. 6A illustrates anexample in which the light-blocking layer 847 is provided between thecoloring layers CFR and CFG, between the coloring layers CFG and CFB,and between the coloring layers CFR and CFY, the light-blocking layer847 is not necessarily provided between these coloring layers. In thisexample, four sub-pixels overlap with one sensing element C2.

As illustrated in FIG. 6B, the EL layers 833 emitting light of differentcolors may be separately provided so that subpixels have different ELlayers 833. The spacer 823 illustrated in FIG. 4A and the like is notnecessarily provided. The conductive layer 856 and the insulating layer817 b illustrated in FIG. 4A and the like are not necessarily provided,and the first electrode 831 may be directly connected to the sourceelectrode or the drain electrode of the transistor.

As illustrated in FIG. 6C, the input/output device does not necessarilyinclude the transistor electrically connected to the light-emittingelement. The conductive layer 857 a and the conductive layer 857 b,which are external connection electrodes, can each be electricallyconnected to an FPC or the like. A conductive layer 814 is preferably,though not necessarily, provided because voltage drop due to theresistance of the first electrode 831 can be inhibited. The conductivelayer 814 may be provided between the first electrode 831 and theinsulating layer 375. In addition, for a similar purpose, a conductivelayer electrically connected to the second electrode 835 may be providedover the insulating layer 375, the EL layer 833, the second electrode835, or the like.

<Specific Example 3 of Cross-Sectional Structure>

FIG. 7 is an example of a cross-sectional view of the input/outputdevice of one embodiment of the present invention.

The input/output device illustrated in FIG. 7 differs from theinput/output device illustrated in FIG. 4A in that a bonding layer 822 aand a fourth bonding layer 822 b are included. The same portions as inthe input/output device illustrated in FIG. 4A are not described here.

In one embodiment of the present invention, the fourth bonding layer 822b with a frame-like shape that surrounds the bonding layer 822 a ispreferably provided.

When a bonding layer that is positioned between the light-emittingelement and the sensing element and is exposed at a side surface of theinput/output device has a low gas barrier property, impurities such asmoisture and oxygen enter the light-emitting element and the like fromthe outside. The entry of impurities into an organic EL element causes,for example, shrinkage of a light-emitting portion (here, luminancedegradation from an end portion of the light-emitting portion, or anincrease in a non-light-emitting region in the light-emitting portion).Thus, the bonding layer that covers an element such as an organic ELelement preferably has an excellent gas barrier property (in particular,low water vapor and oxygen permeability).

In the case where a liquid composition whose volume is greatly reducedby curing is used as a material for the bonding layer, stress is appliedto the light-emitting element, which might damage the light-emittingelement and cause poor light emission.

Thus, a reduction in the volume due to curing of a material for thebonding layer is preferably as small as possible.

In the case where the bonding layer is positioned on the side from whichlight from the light-emitting element is extracted, thelight-transmitting property of the bonding layer is preferably high sothat the light extraction efficiency of the input/output device isincreased.

A plurality of properties are required for the bonding layer asdescribed above, and it is very difficult for the material for thebonding layer to have two or more of those properties.

In view of the above, the bonding layer, which corresponds to theabove-described first bonding layer, is surrounded by the fourthframe-like bonding layer. Two types of bonding layers formed usingdifferent materials are provided, so that the reliability of theinput/output device can be increased. For example, by using the outerbonding layer containing a material having a higher gas barrier propertythan a material for the inner bonding layer, the entry of moisture oroxygen from the outside into the input/output device can be preventedeven when the inner bonding layer is formed using a material that has alow gas barrier property and has a small reduction in volume due tocuring, a high light-transmitting property (visible light transmittance,in particular), or a high refractive index. Thus, a highly reliablelight-emitting device in which shrinkage of a light-emitting portion isinhibited can be obtained. The properties of the two bonding layers arenot limited to the above, and materials having desired properties can beused as appropriate for the bonding layers.

Although an opening is formed in the fourth frame-like bonding layer 822b and the like so that the conductive layers 857 a and 857 b areelectrically connected to the respective FPCs in FIG. 7, an opening maybe formed in the bonding layer 822 a and the like so that the conductivelayer 857 a or the conductive layer 857 b is electrically connected tothe FPC. In that case, a region where the conductive layer 857 a or theconductive layer 857 b is electrically connected to the FPC is alsosurrounded by the fourth frame-like bonding layer 822 b.

<Specific Example 4 of Cross-Sectional Structure>

FIG. 8 is an example of a cross-sectional view of the input/outputdevice of one embodiment of the present invention.

The input/output device illustrated in FIG. 8 differs from theinput/output device illustrated in FIG. 4A in that an edge of thebonding layer 811 is positioned outside the substrate 801 and that anedge of the bonding layer 841 is positioned outside the substrate 803.The same portions as in the input/output device illustrated in FIG. 4Aare not described here.

In one embodiment of the present invention, at least part of the edge ofthe bonding layer 811 is preferably positioned outside an edge of thesubstrate 801.

In addition, in one embodiment of the present invention, at least partof the edge of the bonding layer 841 is preferably positioned outside anedge of the substrate 803.

By providing the bonding layers at the edges of the input/output device,the substrate 801, the substrate 803, and the stacked components betweenthe substrates can be firmly attached to each other. Thus, theinput/output device can be highly resistant to repeated bending andhighly reliable.

In addition, by providing the bonding layers at the edges of theinput/output device, the water resistance and the dust resistance of theinput/output device can be improved, so that the input/output device canbe highly reliable.

Note that a bonding layer may be formed so as to extend to the outsideof the edge of the substrate when the substrate and the insulating layerare attached to each other with the bonding layer, or a bonding layermay be additionally formed at an edge of the input/output device withthe use of an adhesive after the substrate and the insulating layer areattached to each other.

<Specific Example 5 of Cross-Sectional Structure>

FIG. 9A is an example of a cross-sectional view of the input/outputdevice of one embodiment of the present invention.

The input/output device illustrated in FIG. 9A differs from theinput/output device illustrated in FIG. 4A in that a conductive layer857 d that is electrically connected through the connector 825 b to theFPC1, through which a signal is supplied to the input portion, ispositioned over the same substrate as the conductive layer 857 a that iselectrically connected through the connector 825 a to the FPC2, throughwhich a signal is supplied to the display portion. The same portions asin the input/output device illustrated in FIG. 4A are not describedhere.

When both the conductive layer 857 a and the conductive layer 857 d areprovided on one side of the input/output device, the connectionpositions of the FPCs can be determined more flexibly: for example, theFPC1 and the FPC2 can be positioned in the same direction. In addition,a pressure bonding step and a transfer step are unlikely to be limitedbecause an FPC does not have to be pressure bonded to one side of theinput/output device while another FPC is already attached to the otherside of the input/output device. Moreover, connection between an FPC andan IC or the like is unlikely to be limited. In one embodiment of thepresent invention, signals may be supplied from one FPC to the inputportion and the display portion.

The conductive layers 857 b and 857 c on the input portion side areelectrically connected to the conductive layer 857 d and a conductivelayer 857 e through conductive particles 877. The conductive particles877 are provided so as to be dispersed in the bonding layer 822. Thus,the conductive layers 857 b, 857 c, 857 d, and 857 e are electricallyconnected through the conductive particles 877.

As the conductive particles 877, particles of an organic resin, silica,or the like coated with a conductive material such as a metal materialor an alloy material are preferably used. It is preferable to use nickelor gold as the metal material because contact resistance can bedecreased. It is also preferable to use particles each coated withlayers of two or more kinds of metal materials, such as particles coatedwith nickel and further with gold. Alternatively, particles of aconductive material may be used as the conductive particles 877.

It is preferred that the conductive particle 877 is deformed by beingcrushed under vertical pressure. This increases the contact area betweenthe conductive particle 877 and the conductive layers 857 c and 857 e,whereby electrical connection can be surely made. In many actual cases,the conductive particle has a circular cross-sectional shape or anelliptical cross-sectional shape with a long axis in a directionparallel to the substrates.

As illustrated in FIG. 9B, a resin layer 877 b in which conductiveparticles 877 a are dispersed may be provided. The resin layer 877 b maybe formed using a material different from that for the bonding layer822. For example, a curable organic resin such as a heat curable organicresin or a photocurable organic resin can be used. The conductiveparticles 877 a in the resin layer 877 b are in contact with both theconductive layer 857 c and the conductive layer 857 e, whereby theconductive layer 857 c and the conductive layer 857 e are electricallyconnected to each other.

Materials for the conductive particle 877 a and the resin layer 877 bcan be collectively called an anisotropic conductive paste. For example,a material in which conductive particles are dispersed in a resin suchas an epoxy resin can be used. By using the material having anisotropicconductivity, the plurality of conductive layers 857 b on the inputportion side can be electrically connected to the respective conductivelayers 857 d on the display portion side.

<Examples of Materials>

Next, materials and the like that can be used for the input/outputdevice are described. Note that description on the components alreadydescribed in this specification is omitted in some cases.

For each of the substrates, a material such as glass, quartz, an organicresin, a metal, or an alloy can be used. The substrate on the side fromwhich light from the light-emitting element is extracted is formed usinga material that transmits the light.

It is particularly preferable to use a flexible substrate. For example,an organic resin; a glass material, a metal, or an alloy that is thinenough to have flexibility; or the like can be used.

An organic resin, which has a specific gravity smaller than that ofglass, is preferably used for the flexible substrate, in which case theinput/output device can be more lightweight than in the case where glassis used.

The substrate is preferably formed using a material with high toughness.In that case, the input/output device can have high impact resistanceand can be less likely to be broken. For example, when an organic resinsubstrate or a thin metal or alloy substrate is used, the input/outputdevice can be more lightweight and less likely to be broken than in thecase where a glass substrate is used.

A metal material and an alloy material, which have high thermalconductivity, are preferable because they can easily conduct heat to thewhole substrate and accordingly can prevent a local temperature rise inthe input/output device. The thickness of a substrate using a metalmaterial or an alloy material is preferably greater than or equal to 10μm and less than or equal to 200 μm, further preferably greater than orequal to 20 μm and less than or equal to 50 μm.

There is no particular limitation on the material for the metalsubstrate or the alloy substrate, but it is preferable to use, forexample, aluminum, copper, nickel, a metal alloy such as an aluminumalloy or stainless steel.

Furthermore, when a material with high thermal emissivity is used forthe substrate, the surface temperature of the input/output device can beprevented from rising, leading to prevention of breakage or a decreasein the reliability of the input/output device. For example, thesubstrate may have a stacked-layer structure of a metal substrate and alayer with high thermal emissivity (e.g., the layer can be formed usinga metal oxide or a ceramic material).

Examples of a material having flexibility and a light-transmittingproperty include polyester resins such as polyethylene terephthalate(PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, apolyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC)resin, a polyethersulfone (PES) resin, a polyamide resin, a cycloolefinresin, a polystyrene resin, a polyamide imide resin, and a polyvinylchloride resin. In particular, a material whose coefficient of thermalexpansion is low is preferred, and for example, a polyamide imide resin,a polyimide resin, or PET can be suitably used. A substrate in which afibrous body is impregnated with a resin (also referred to as prepreg)or a substrate whose coefficient of thermal expansion is reduced bymixing an organic resin with an inorganic filler can also be used.

The flexible substrate may have a stacked-layer structure in which ahard coat layer (such as a silicon nitride layer) by which a surface ofthe device is protected from damage, a layer (such as an aramid resinlayer) that can disperse pressure, or the like is stacked over a layerof any of the above-mentioned materials.

The flexible substrate may be formed by stacking a plurality of layers.When a glass layer is used, a barrier property against water and oxygencan be improved, leading to a highly reliable input/output device.

A flexible substrate in which a glass layer, a bonding layer, and anorganic resin layer are stacked from the side closer to a light-emittingelement is preferably used. The thickness of the glass layer is greaterthan or equal to 20 μm and less than or equal to 200 μm, preferablygreater than or equal to 25 μm and less than or equal to 100 μm. Withsuch a thickness, the glass layer can have both a high barrier propertyagainst water and oxygen and high flexibility. The thickness of theorganic resin layer is greater than or equal to 10 μm and less than orequal to 200 μm, preferably greater than or equal to 20 μm and less thanor equal to 50 μm. Providing such an organic resin layer outside theglass layer, breakage or a crack of the glass layer can be inhibited,resulting in increased mechanical strength. With the substrate thatincludes such a composite material for a glass material and an organicresin, the input/output device can be highly reliable and flexible.

Any of a variety of curable adhesives, e.g., light curable adhesivessuch as a UV curable adhesive, a reactive curable adhesive, a thermalcurable adhesive, and an anaerobic adhesive can be used for the adhesivelayer. Examples of these adhesives include an epoxy resin, an acrylicresin, a silicone resin, a phenol resin, a polyimide resin, an imideresin, a polyvinyl chloride (PVC) resin, a polyvinyl butyral (PVB)resin, and an ethylene vinyl acetate (EVA) resin. In particular, amaterial with low moisture permeability, such as an epoxy resin, ispreferred. Alternatively, a two-component-mixture-type resin may beused. Further alternatively, an adhesive sheet or the like may be used.

Furthermore, the resin may include a drying agent. For example, asubstance that adsorbs moisture by chemical adsorption, such as an oxideof an alkaline earth metal (e.g., calcium oxide or barium oxide), can beused. Alternatively, a substance that adsorbs moisture by physicaladsorption, such as zeolite or silica gel, may be used. The drying agentis preferably included, in which case it can prevent entry of impuritiessuch as moisture into the functional element and can improve thereliability of the input/output device.

In addition, it is preferable to mix a filler with a high refractiveindex or light-scattering member into the resin, in which case theefficiency of light extraction from the light-emitting element can beimproved. For example, titanium oxide, barium oxide, zeolite, zirconium,or the like can be used.

The structure of the transistors in the input/output device is notparticularly limited. For example, a forward staggered transistor or aninverted staggered transistor may be used. A top-gate transistor or abottom-gate transistor may be used. There is no particular limitation onthe semiconductor material that is used for the transistors, and forexample, an oxide semiconductor, silicon, germanium, or an organicsemiconductor can be used.

There is no particular limitation on the state of the semiconductormaterial used for the transistors, and an amorphous semiconductor or asemiconductor having crystallinity (a microcrystalline semiconductor, apolycrystalline semiconductor, a single crystal semiconductor, or asemiconductor partly including crystal regions) may be used. Asemiconductor having crystallinity is preferably used, in which casedeterioration of the transistor characteristics can be suppressed.

For example, for the semiconductor layer, an element belonging to Group4, a compound semiconductor, or an oxide semiconductor can be used.Specifically, a semiconductor containing silicon, a semiconductorcontaining gallium arsenide, an oxide semiconductor containing indium,or the like can be used.

An oxide semiconductor is preferably used as a semiconductor where achannel of the transistor is formed. In particular, an oxidesemiconductor having a wider band gap than silicon is preferably used. Asemiconductor material having a wider band gap and a lower carrierdensity than silicon is preferably used, in which case the off-stateleakage current of the transistor can be reduced.

For example, the oxide semiconductor preferably contains at least indium(In) or zinc (Zn). Further preferably, the oxide semiconductor isIn-M-Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La,Ce, or Hf).

As the semiconductor layer, it is preferable to use an oxidesemiconductor film including a plurality of crystal parts. Specifically,the c-axes of the crystal parts are oriented substantially perpendicularto a surface on which the semiconductor layer is formed or the topsurface of the semiconductor layer, and adjacent crystal parts have nograin boundary.

Such an oxide semiconductor without grain boundary prevents a crack ofan oxide semiconductor film from being caused by stress generated whenthe input/output device is bent. Consequently, such an oxidesemiconductor is preferably used for a flexible input/output device thatis bent when used.

The use of such an oxide semiconductor for the semiconductor layerachieves a highly reliable transistor with little change in theelectrical characteristics.

Charge accumulated in a capacitor through a transistor can be retainedfor a long time because of low off-state current of the transistor. Theuse of such a transistor in pixels allows a driver circuit to stop whilethe luminance of an image displayed on display regions of the pixels ismaintained. As a result, the input/output device can have extremely lowpower consumption.

Alternatively, silicon is preferably used as a semiconductor in which achannel of a transistor is formed. Silicon may be amorphous silicon butis preferably silicon having crystallinity, such as microcrystallinesilicon, polycrystalline silicon, or single crystal silicon. Inparticular, polycrystalline silicon can be formed at a lower temperaturethan single crystal silicon and has higher field-effect mobility andhigher reliability than amorphous silicon. When such a polycrystallinesemiconductor is used for a pixel, the aperture ratio of the pixel canbe increased. Even when pixels are provided at very high density, a gatedriver circuit and a source driver circuit can be formed over asubstrate where the pixels are formed, so that the number of componentsof an electronic appliance can be reduced.

For stable characteristics of the transistor, a base film is preferablyprovided. The base film can be formed with a single-layer structure or astacked-layer structure using an inorganic insulating film such as asilicon oxide film, a silicon nitride film, a silicon oxynitride film,or a silicon nitride oxide film. The base film can be formed bysputtering, chemical vapor deposition (CVD) such as a plasma-enhancedCVD, thermal CVD, or metal organic CVD (MOCVD), atomic layer deposition(ALD), coating, printing, or the like. Note that the base film is notnecessarily provided. In each of the above structure examples, theinsulating layer 813 can also serve as a base film of the transistor.

As the light-emitting element, a self-luminous element can be used, andan element whose luminance is controlled by current or voltage isincluded in the category of the light-emitting element. For example, alight-emitting diode (LED), an organic EL element, or an inorganic ELelement can be used.

A conductive film that transmits visible light is used for the electrodethrough which light from the light-emitting element is extracted. Aconductive film that reflects visible light is preferably used for theelectrode through which light is not extracted.

The conductive film that transmits visible light can be formed using,for example, indium oxide, indium tin oxide (ITO), indium zinc oxide,zinc oxide, or zinc oxide to which gallium is added. It is also possibleto use a film of a metal material such as gold, silver, platinum,magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper,palladium, or titanium; an alloy containing any of these metalmaterials; or a nitride of any of these metal materials (e.g., titaniumnitride) when the film is thin enough to have a light-transmittingproperty. Alternatively, a stack of any of the above materials can beused as the conductive film. For example, a stacked film of ITO and analloy of silver and magnesium is preferably used, in which caseconductivity can be increased. Further alternatively, graphene or thelike may be used.

For the conductive film that reflects visible light, a metal materialsuch as aluminum, gold, platinum, silver, nickel, tungsten, chromium,molybdenum, iron, cobalt, copper, or palladium or an alloy containingany of these metal materials can be used, for example. Lanthanum,neodymium, germanium, or the like may be added to the metal material orthe alloy. Moreover, the conductive film can be formed using an alloycontaining aluminum (an aluminum alloy) such as an alloy of aluminum andtitanium, an alloy of aluminum and nickel, or an alloy of aluminum andneodymium; or an alloy containing silver such as an alloy of silver andcopper, an alloy of silver, palladium, and copper, or an alloy of silverand magnesium. An alloy of silver and copper is preferable because ofits high heat resistance. When a metal film or a metal oxide film isstacked on an aluminum alloy film, oxidation of the aluminum alloy filmcan be suppressed. Examples of a material for the metal film or themetal oxide film are titanium and titanium oxide. Alternatively, theconductive film having a property of transmitting visible light and afilm containing any of the above metal materials may be stacked. Forexample, it is possible to use a stacked film of silver and ITO or astacked film of an alloy of silver and magnesium and ITO.

Each of the electrodes can be formed by an evaporation method or asputtering method. Alternatively, a discharging method such as anink-jet method, a printing method such as a screen printing method, or aplating method can be used.

When a voltage higher than the threshold voltage of the light-emittingelement is applied between the first electrode 831 and the secondelectrode 835, holes are injected to the EL layer 833 from the anodeside and electrons are injected to the EL layer 833 from the cathodeside. The injected electrons and holes are recombined in the EL layer833 and a light-emitting substance contained in the. EL layer 833 emitslight.

The EL layer 833 includes at least a light-emitting layer. In additionto the light-emitting layer, the EL layer 833 may further include one ormore layers containing any of a substance with a high hole-injectionproperty, a substance with a high hole-transport property, ahole-blocking material, a substance with a high electron-transportproperty, a substance with a high electron-injection property, asubstance with a bipolar property (a substance with a highelectron-transport property and a high hole-transport property), and thelike.

For the EL layer 833, either a low molecular compound or a highmolecular compound can be used, and an inorganic compound may be used.Each of the layers included in the EL layer 833 can be formed by any ofthe following methods: an evaporation method (including a vacuumevaporation method), a transfer method, a printing method, an ink jetmethod, a coating method, and the like.

The light-emitting element is preferably provided between a pair ofinsulating films that are highly resistant to moisture, in which caseimpurities such as water can be prevented from entering thelight-emitting element, thereby preventing a decrease in the reliabilityof the input/output device.

Examples of the insulating film with high resistance to moisture includea film containing nitrogen and silicon (e.g., a silicon nitride film anda silicon nitride oxide film) and a film containing nitrogen andaluminum (e.g., an aluminum nitride film). Alternatively, a siliconoxide film, a silicon oxynitride film, an aluminum oxide film, or thelike may be used.

For example, the moisture vapor transmission rate of the insulating filmwith high resistance to moisture is lower than or equal to1×10⁻⁵[g/(m²·day)], preferably lower than or equal to1×10⁻⁶[g/(m²·day)], further preferably lower than or equal to1×10⁻⁷[g/(m²·day)], still further preferably lower than or equal to1×10⁻⁸[g/(m²·day)].

Insulating films with high resistance to moisture are preferably used asthe insulating layer 813 and the insulating layer 843.

As each of the insulating layers 812, 815, and 842, an inorganicinsulating film such as a silicon oxide film, a silicon oxynitride film,a silicon nitride film, a silicon nitride oxide film, or an aluminumoxide film can be used, for example. For each of the insulating layers817, 817 a, 817 b, and 852, an organic material such as polyimide,acrylic, polyamide, polyimide amide, or a benzocyclobutene-based resincan be used, for example. Alternatively, a low dielectric constantmaterial (low-k material) or the like can be used. Furthermore, each ofthe insulating layers may be formed by stacking a plurality ofinsulating films.

The insulating layer 821 is formed using an organic insulating materialor an inorganic insulating material. As a resin, for example, apolyimide resin, a polyamide resin, an acrylic resin, a siloxane resin,an epoxy resin, or a phenol resin can be used. It is particularlypreferable that the insulating layer 821 be formed to have an inclinedsidewall with continuous curvature by using a photosensitive resinmaterial.

There is no particular limitation on the method for forming theinsulating layer 821. A photolithography method, a sputtering method, anevaporation method, a droplet discharging method (e.g., an ink jetmethod), a printing method (e.g., screen printing or off-set printing),or the like may be used.

The spacer 823 can be formed using an inorganic insulating material, anorganic insulating material, a metal material, or the like. As theinorganic insulating material and the organic insulating material, avariety of materials that can be used for the aforementioned insulatinglayers can be used, for example. As the metal material, titanium,aluminum, or the like can be used. When the spacer 823 containing aconductive material and the second electrode 835 are electricallyconnected to each other, a potential drop due to the resistance of thesecond electrode 835 can be suppressed. The spacer 823 may have atapered shape or an inverse tapered shape.

The conductive layer that functions as an electrode of the transistor, awiring, an auxiliary wiring of the light-emitting element, or the likein the input/output device (the input portion and the display portion)can be formed to have a single-layer structure or a layered structureusing any of metal materials such as molybdenum, titanium, chromium,tantalum, tungsten, aluminum, copper, neodymium, and scandium, and analloy material containing any of these elements. Alternatively, theconductive layer may be formed using a conductive metal oxide. As theconductive metal oxide, indium oxide (e.g., In₂O₃), tin oxide (e.g.,SnO₂), zinc oxide (ZnO), ITO, indium zinc oxide (e.g., In₂O₃—ZnO), orany of these metal oxide materials in which silicon oxide is containedcan be used.

The coloring layer is a colored layer that transmits light in a specificwavelength range. For example, a red (R) color filter for transmittinglight in a red wavelength range, a green (G) color filter fortransmitting light in a green wavelength range, and a blue (B) colorfilter for transmitting light in a blue wavelength range can be used.Each coloring layer is formed in a desired position with any of variousmaterials by a printing method, an ink-jet method, an etching methodusing photolithography, or the like. The coloring layer can be formedusing a metal material, pigment, dye, or the like.

The light-blocking layer is provided between adjacent coloring layers.The light-blocking layer blocks light emitted from an adjacentlight-emitting element to prevent color mixture between adjacentlight-emitting elements. Here, the coloring layer is provided such thatits end portion overlaps with the light-blocking layer, whereby lightleakage can be reduced. For the light-blocking layer, a material thatblocks light from the light-emitting element can be used; for example, ablack matrix can be formed using carbon black; a metal oxide; acomposite oxide containing a solid solution of a plurality of metaloxides; or a resin material containing a metal material, pigment, ordye. Note that it is preferable to provide the light-blocking layer in aregion other than the light-emitting unit, such as the driver circuitunit, in which case undesired leakage of guided light or the like can besuppressed.

An overcoat that covers the coloring layer and the light-blocking layermay be provided. The overcoat can prevent impurities and the likecontained in the coloring layer from being diffused into thelight-emitting element. The overcoat is formed with a material thattransmits light emitted from the light-emitting element; for example, itis possible to use an inorganic insulating film such as a siliconnitride film or a silicon oxide film, an organic insulating film such asan acrylic film or a polyimide film, or a stacked layer of an organicinsulating film and an inorganic insulating film.

For the connector, it is possible to use a paste-like or sheet-likematerial that is obtained by mixing metal particles into a thermosettingresin and exhibits anisotropic electrical conductivity bythermocompression bonding. As the metal particles, particles in whichtwo or more kinds of metals are layered, for example, nickel particlescoated with gold are preferably used.

Note that the input/output device of one embodiment of the presentinvention may include a display element other than the light-emittingelement.

Note that in this specification and the like, a display element, adisplay device including a display element, a light-emitting element,and a light-emitting device including a light-emitting element canemploy various modes or can include various elements. A display element,a display device, a light-emitting element, or a light-emitting deviceincludes at least one of the following, for example: an EL element(e.g., an EL element including organic and inorganic materials, anorganic EL element, and an inorganic EL element), an LED (e.g., a whiteLED, a red LED, a green LED, and a blue LED), a transistor (a transistorthat emits light depending on current), an electron emitter, a liquidcrystal element, electronic ink, an electrophoretic element, a gratinglight valve (GLV), a plasma display panel (PDP), a display element usingmicro electro mechanical system (MEMS), a digital micromirror device(DMD), a digital micro shutter (DMS), an interferometric modulator(IMOD) element, a MEMS shutter display element, anoptical-interference-type MEMS display element, an electrowettingelement, a piezoelectric ceramic display, and a display element using acarbon nanotube. Other than the above, a display medium whose contrast,luminance, reflectance, transmittance, or the like is changed byelectric or magnetic action may be included. An example of a displaydevice having EL elements is an EL display. Examples of a display deviceincluding electron emitters are a field emission display (FED) and anSED-type flat panel display (SED: surface-conduction electron-emitterdisplay). An example of a display device including liquid crystalelements is a liquid crystal display (e.g., a transmissive liquidcrystal display, a transflective liquid crystal display, a reflectiveliquid crystal display, a direct-view liquid crystal display, and aprojection liquid crystal display). An example of a display device usingelectronic ink, Electronic Liquid Powder (registered trademark), orelectrophoretic elements is electronic paper. In a transflective liquidcrystal display or a reflective liquid crystal display, some or all ofpixel electrodes function as reflective electrodes. For example, some orall of pixel electrodes are formed to contain aluminum, silver, or thelike. In such a case, a memory circuit such as SRAM can be providedunder the reflective electrodes, leading to lower power consumption.

For example, in this specification and the like, it is possible toemploy an active matrix method in which an active element (a non-linearelement) is included in a pixel or a passive matrix method in which anactive element is not included in a pixel.

In the active matrix method, not only a transistor but also a variety ofactive elements, for example, a metal insulator metal (MIM) or a thinfilm diode (TFD) can be used. These elements are fabricated with a smallnumber of steps, resulting in low manufacturing cost or high yield.Furthermore, since these elements are small, the aperture ratio can beincreased, leading to low power consumption and high luminance.

Since an active element is not used in the passive matrix method, thenumber of manufacturing steps is small, so that the manufacturing costcan be reduced or the yield can be increased. Furthermore, since anactive element is not used, the aperture ratio can be improved, leadingto low power consumption or high luminance.

Note that the input/output device of one embodiment of the presentinvention may be used not only as a display device but also as alighting device. By using the light-emitting device as a lightingdevice, it can be used for interior lighting having an attractive designor as lighting from which light radiates in various directions.Alternatively, the light-emitting device may be used as a light sourcesuch as a backlight or a front light, that is, a lighting device for adisplay panel.

Note that although the capacitive touch sensor is used in thisembodiment, one embodiment of the present invention is not limitedthereto. For example, a variety of sensors (e.g., an optical sensorusing a photoelectric conversion element and a pressure-sensitive sensorusing a pressure-sensitive element) that can sense the approach or thecontact of a sensing target such as a finger, another sensing element,or another input device may be used.

As described above, in one embodiment of the present invention, aneutral plane where distortion due to stress such as compressive stressor tensile stress against deformation such as bending does not occur (aplane that does not expand or contract) is positioned in the EL layer ornear the EL layer. Thus, separation of the EL layer due to bending canbe inhibited, so that the input/output device can be highly reliable.Moreover, the input/output device can have high resistance to repeatedbending.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 2

In this embodiment, an input portion that can be used in theinput/output device of one embodiment of the present invention isdescribed.

<Structure Example 1 of Input Device>

FIGS. 10A, 10B, 10C-1, and 10C-2 illustrate a structure of the inputportion 600. FIG. 10A is a block diagram illustrating the structure ofthe input portion 600. FIG. 10B is a circuit diagram illustratingconfigurations of a converter CONV and a sensing unit 10U. FIGS. 10C-1and 10C-2 are timing charts for explaining a method for driving thesensing unit 10U.

The input portion 600 described in this embodiment includes a pluralityof sensing units 10U arranged in a matrix, selection signal lines G1 towhich the sensing units 10U arranged in the row direction areelectrically connected, signal lines DL to which the sensing units 10Uarranged in the column direction are electrically connected, and thefirst substrate 101 provided with the sensing units 10U, the selectionsignal lines G1, and the signal lines DL (see FIG. 10A).

For example, the plurality of sensing units 10U can be arranged in amatrix of n rows and m columns (n and m are each a natural number of 1or more).

The sensing unit 10U includes a sensing element C having the secondelectrode 12 electrically connected to a wiring CS. Thus, the potentialof the second electrode 12 of the sensing element C can be controlledusing a control signal supplied through the wiring CS.

The sensing unit 10U includes a first transistor M1 in which a gate iselectrically connected to the first electrode 11 of the sensing elementC and a first electrode is electrically connected to a wiring VPI (seeFIG. 10B). The wiring VPI can supply, for example, a ground potential.

The sensing unit 10U may include a second transistor M2 in which a gateis electrically connected to the selection signal line G1, a firstelectrode is electrically connected to a second electrode of the firsttransistor M1, and a second electrode is electrically connected to thesignal line DL. The selection signal line G1 can supply a selectionsignal. The signal line DL can supply, for example, the sensing signalDATA.

The sensing unit 10U may include a third transistor M3 in which a gateis electrically connected to a wiring RES, a first electrode iselectrically connected to the first electrode 11 of the sensing elementC, and a second electrode is electrically connected to a wiring VRES.The wiring RES can supply a reset signal. The wiring VRES can supply,for example, a potential capable of turning on the first transistor M1.

The capacitance of the sensing element C is changed when an object comesclose to the first electrode 11 or the second electrode 12 or when thedistance between the first electrode 11 and the second electrode 12 ischanged, for example. Thus, the sensing unit 10U can supply the sensingsignal DATA based on a change in the capacitance of the sensing elementC or parasitic capacitance.

The sensing unit 10U includes the wiring CS that can supply a controlsignal capable of controlling the potential of the second electrode 12of the sensing element C.

A node where the first electrode 11 of the sensing element C, the gateof the first transistor M1, and the first electrode of the thirdtransistor M3 are electrically connected is referred to as a node A.

The wiring VPI can supply, for example, a ground potential. The wiringVRES, a wiring VPO, and a wiring BR can supply, for example, a highpower supply potential sufficient to turn on a transistor.

The wiring RES can supply a reset signal. The selection signal line G1can supply a selection signal. The wiring CS can supply a control signalfor controlling the potential of the second electrode 12 of the sensingelement C. Note that the second electrode 12 may also serve as thewiring CS.

The signal line DL can supply the sensing signal DATA. A terminal OUTcan supply a signal obtained by conversion based on the sensing signalDATA.

A driver circuit GD can supply, for example, a selection signal at giventimings. The converter CONV has a conversion circuit. A variety ofcircuits that can convert the sensing signal DATA and supply theresulting signal to the terminal OUT can be used for the converter CONV.For example, a source follower circuit or a current mirror circuit maybe configured by electrically connecting the converter CONV to thesensing unit 10U.

Specifically, a source follower circuit can be configured with theconverter CONV using a transistor M4 (see FIG. 10B). Note that thetransistor M4 may be a transistor that can be fabricated in the samesteps as the first to third transistors M1 to M3.

<Method for Driving Sensing Unit 10U>

A method for driving the sensing unit 10U is described.

<<First Step>>

In a first step, a reset signal for turning on the third transistor M3and subsequently turning off the third transistor M3 is supplied to thegate of the third transistor M3, and a potential of the first electrode11 of the sensing element C is set at a predetermined potential (seePeriod T1 in FIG. 10C-1).

Specifically, a reset signal is supplied from the wiring RES. The thirdtransistor M3 supplied with the reset signal makes the node A have apotential capable of turning on the first transistor M1, for example(see FIG. 10B).

<<Second Step>>

In a second step, a selection signal for turning on the secondtransistor M2 is supplied to the gate of the second transistor M2, andthe second electrode of the first transistor M1 is made electricallyconnected to the signal line DL.

Specifically, a selection signal is supplied from the selection signalline G1. The second transistor M2 supplied with the selection signalelectrically connects the second electrode of the first transistor M1 tothe signal line DL (see Period T2 in FIG. 10C-1).

<<Third Step>>

In a third step, a control signal is supplied to the second electrode 12of the sensing element C, and a potential that varies depending on thecontrol signal and the capacitance of the sensing element C is suppliedto the gate of the first transistor M1.

Specifically, a rectangular control signal is supplied from the wiringCS. With supply of the rectangular control signal to the secondelectrode 12, the potential of the node A rises depending on thecapacitance of the sensing element C (see the latter half of Period T2in FIG. 10C-1).

For example, when the sensing element C is placed in the air and anobject with a higher dielectric constant than the air comes close to thesecond electrode 12 of the sensing element C, the apparent capacitanceof the sensing element C increases.

Consequently, a change in the potential of the node A due to arectangular control signal is smaller than that when an object with ahigher dielectric constant than the air is not placed close to thesecond electrode of the sensing element C (see a solid line in FIG.10C-2).

<<Fourth Step>>

In a fourth step, a signal based on a change in the gate potential ofthe first transistor M1 is supplied to the signal line DL.

For example, a current that is changed on the basis of a change in thegate potential of the first transistor M1 is supplied to the signal lineDL.

The converter CONV converts a change in current flowing through thesignal line DL into a change in voltage and outputs the voltage.

<<Fifth Step>>

In a fifth step, a selection signal for turning off the secondtransistor M2 is supplied to the gate of the second transistor M2.

The first to fifth steps are repeated for every row of the selectionsignal lines G1(1) to G1(n).

<Structure Example 2 of Input Device>

FIGS. 11A to 11C illustrate a structure of an input portion 600B. FIG.11A is a block diagram illustrating the structure of the input portion600B. FIG. 11B is a circuit diagram illustrating structures of aconverter CONV and a sensing unit 10UB. FIG. 11C is a timing chart forexplaining a method for driving the sensing unit 10UB.

The input portion 600B differs from the input portion 600 in that thesensing unit 10UB is provided instead of the sensing unit 10U.

The sensing unit 10UB differs from the sensing unit 10U in the followingtwo aspects. The first aspect is that the second electrode 12 of thesensing element C is electrically connected to the selection signal lineG1. The second aspect is that the second electrode of the firsttransistor M1 in the sensing unit 10UB is electrically connected to thesignal line DL without through the second transistor M2. Here, differentstructures are described in detail, and the above description isreferred to for the other similar structures.

The input portion 600B includes the plurality of sensing units 10UBarranged in a matrix, selection signal lines G1 to which the sensingunits 10UB arranged in the row direction are electrically connected,signal lines DL to which the sensing units 10UB arranged in the columndirection are electrically connected, and the first substrate 101provided with the sensing units 10UB, the selection signal lines G1, andthe signal lines DL (see FIG. 11A).

For example, the plurality of sensing units 10UB can be arranged in amatrix of n rows and m columns (n and m are each a natural number of 1or more).

The sensing unit 10UB includes the sensing element C having the secondelectrode 12 electrically connected to the selection signal line G1.Thus, the potential of the second electrode 12 of the sensing element Ccan be controlled using a selection signal for each group of sensingunits 10UB electrically connected to one selected selection signal lineG1.

The selection signal line G1 can be a wiring formed using a conductivefilm that can be formed in the same steps as the signal line DL.

Alternatively, the selection signal line G1 may be a wiring formed usinga conductive film that can be formed in the same steps as the secondelectrode 12 of the sensing element C. For example, the secondelectrodes 12 in the sensing units 10UB adjacent in the row directioncan be connected to each other and the connected second electrodes canbe used as the selection signal line G1.

A method for driving the sensing unit 10UB is described.

<<First Step>>

In a first step, a reset signal for turning on the third transistor M3and subsequently turning off the third transistor M3 is supplied to thegate of the third transistor M3, and a potential of the first electrode11 of the sensing element C is set at a predetermined potential (seePeriod T1 in FIG. 11C).

Specifically, a reset signal is supplied from the wiring RES. The thirdtransistor M3 supplied with the reset signal makes the node A have apotential capable of turning on the first transistor M1, for example(see FIG. 11B).

<<Second Step>>

In a second step, a selection signal is supplied to the second electrode12 of the sensing element C, and a potential that varies depending onthe selection signal and the capacitance of the sensing element C issupplied to the gate of the first transistor M1 (see Period T2 in FIG.11C).

Specifically, a rectangular selection signal is supplied from theselection signal line G1(i-1). With supply of the rectangular selectionsignal to the second electrode 12, the potential of the node A risesdepending on the capacitance of the sensing element C.

For example, in the case where the sensing element C is placed in theair and an object with a higher dielectric constant than the air isplaced close to the second electrode 12 of the sensing element C, theapparent capacitance of the sensing element C increases.

Consequently, a change in the potential of the node A due to arectangular control signal is smaller than that in the case where anobject with a higher dielectric constant than the air is not placedclose to the second electrode of the sensing element C.

<<Third Step>>

In a third step, a signal based on a change in the gate potential of thefirst transistor M1 is supplied to the signal line DL.

For example, a current that is changed on the basis of a change in thegate potential of the first transistor M1 is supplied to the signal lineDL.

The converter CONV converts a change in current flowing through thesignal line DL into a change in voltage, and the terminal OUT outputsthe voltage.

The first to third steps are repeated for every row of the selectionsignal lines G1(1) to G1(n) (see Periods T2 to T4 in FIG. 11C).

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 3

In this embodiment, a method for manufacturing a flexible input/outputdevice of one embodiment of the present invention is described.

First, a separation layer 203 is formed over a formation substrate 201,and a layer 205 to be separated (hereinafter referred to simply as alayer 205) is formed over the separation layer 203 (see FIG. 12A).Moreover, a separation layer 223 is formed over a formation substrate221, and a layer 225 to be separated (hereinafter referred to simply asa layer 225) is formed over the separation layer 223 (see FIG. 12B).

Although an example in which the separation layer is formed to have anisland shape is described here, one embodiment of the present inventionis not limited to this example. In this step, the material for theseparation layer is selected such that separation occurs at theinterface between the formation substrate and the separation layer, theinterface between the separation layer and the layer to be separated, orin the separation layer when the layer to be separated is separated fromthe formation substrate. Although an example in which separation occursat the interface between the separation layer and the layer to beseparated is described in this embodiment, one embodiment of the presentinvention is not limited to such an example and depends on materialsused for the separation layer and the layer to be separated. Note thatin the case where the layer to be separated has a stacked-layerstructure, a layer in contact with the separation layer is particularlyreferred to as a first layer.

For example, when the separation layer has a stacked-layer structure ofa tungsten film and a tungsten oxide film and separation occurs at theinterface between the tungsten film and the tungsten oxide film (or thevicinity of the interface), part of the separation layer (here, part ofthe tungsten oxide film) may remain on the layer to be separated.Moreover, the separation layer remaining on the layer to be separatedmay be removed after separation.

As the formation substrate, a substrate having heat resistance highenough to withstand at least the process temperature in a manufacturingprocess is used. As the formation substrate, for example, a glasssubstrate, a quartz substrate, a sapphire substrate, a semiconductorsubstrate, a ceramic substrate, a metal substrate, a resin substrate, ora plastic substrate can be used.

When a glass substrate is used as the formation substrate, an insulatingfilm such as a silicon oxide film, a silicon oxynitride film, a siliconnitride film, or a silicon nitride oxide film is preferably formed as abase film between the formation substrate and the separation layer, inwhich case contamination from the glass substrate can be prevented.

The separation layer can be formed using an element selected fromtungsten, molybdenum, titanium, tantalum, niobium, nickel, cobalt,zirconium, zinc, ruthenium, rhodium, palladium, osmium, iridium, andsilicon; an alloy material containing any of the elements; a compoundmaterial containing any of the elements; or the like. A crystalstructure of a layer containing silicon may be amorphous, microcrystal,or polycrystal. Furthermore, a metal oxide such as aluminum oxide,gallium oxide, zinc oxide, titanium dioxide, indium oxide, indium tinoxide, indium zinc oxide, or In—Ga—Zn oxide may be used. The separationlayer is preferably formed using a high-melting point metal materialsuch as tungsten, titanium, or molybdenum, in which case the degree offreedom of the process for forming the layer to be separated can beincreased.

The separation layer can be formed by, for example, a sputtering method,a plasma-enhanced CVD method, a coating method (including a spin coatingmethod, a droplet discharging method, and a dispensing method), or aprinting method. The thickness of the separation layer ranges from 10 nmto 200 nm, for example, and preferably from 20 nm to 100 nm.

When the separation layer has a single-layer structure, a tungstenlayer, a molybdenum layer, or a layer containing a mixture of tungstenand molybdenum is preferably formed. Alternatively, a layer containingan oxide or an oxynitride of tungsten, a layer containing an oxide or anoxynitride of molybdenum, or a layer containing an oxide or anoxynitride of a mixture of tungsten and molybdenum may be formed. Notethat a mixture of tungsten and molybdenum is an alloy of tungsten andmolybdenum, for example.

When the separation layer has a stacked-layer structure including alayer containing tungsten and a layer containing an oxide of tungsten,the layer containing an oxide of tungsten may be formed as follows: thelayer containing tungsten is formed first and an insulating film formedof an oxide is formed thereover, so that the layer containing an oxideof tungsten is formed at the interface between the tungsten layer andthe insulating film. Alternatively, the layer containing an oxide oftungsten may be formed by performing thermal oxidation treatment, oxygenplasma treatment, nitrous oxide (N₂O) plasma treatment, treatment with ahighly oxidizing solution such as ozone water, or the like on thesurface of the layer containing tungsten. Plasma treatment or heattreatment may be performed in an atmosphere of oxygen, nitrogen, ornitrous oxide alone, or a mixed gas of any of these gasses and anothergas. Surface condition of the separation layer is changed by the plasmatreatment or heat treatment, whereby adhesion between the separationlayer and the insulating film formed later can be controlled.

Note that the separation layer is not necessarily provided in the casewhere separation at an interface between the formation substrate and thelayer to be separated is possible. For example, a glass substrate isused as the formation substrate, and an organic resin such as polyimide,polyester, polyolefin, polyamide, polycarbonate, or acrylic is formed incontact with the glass substrate. Next, adhesion between the formationsubstrate and the organic resin is increased by laser light irradiationor heat treatment. Then, an insulating film, a transistor, and the likeare formed over the organic resin. After that, separation at theinterface between the formation substrate and the organic resin can beperformed by performing laser light irradiation with higher energydensity than the above laser light irradiation or performing heattreatment at a higher temperature than the above heat treatment.Moreover, the interface between the formation substrate and the organicresin may be soaked in a liquid to perform separation.

Since the insulating film, the transistor, and the like are formed overthe organic resin having low heat resistance in the above method, it isimpossible to expose the substrate to high temperatures in themanufacturing process. Note that a transistor using an oxidesemiconductor is not necessarily processed at high temperatures and thuscan be favorably formed over the organic resin.

The organic resin may be used for a substrate of the device.Alternatively, the organic resin may be removed and another substratemay be bonded to an exposed surface of the layer to be separated withthe use of an adhesive.

Alternatively, separation at the interface between a metal layer and theorganic resin may be performed in the following manner: the metal layeris provided between the formation substrate and the organic resin andcurrent is made to flow in the metal layer so that the metal layer isheated.

There is no particular limitation on a layer formed as the layer to beseparated.

The insulating layers 813 and 843 formed in contact with the separationlayer preferably has a single-layer structure or a stacked-layerstructure including any of a silicon nitride film, a silicon oxynitridefilm, a silicon oxide film, a silicon nitride oxide film, and the like.

The insulating layers 813 and 843 can be formed by a sputtering method,a plasma-enhanced CVD method, a coating method, a printing method, orthe like. For example, the insulating layer is formed at temperaturesranging from 250° C. to 400° C. by a plasma-enhanced CVD method, wherebythe insulating layer can be a dense film with high moisture resistance.The thickness of the insulating layer ranges preferably from 10 nm to3000 nm, more preferably from 200 nm to 1500 nm.

Next, the formation substrate 201 and the formation substrate 221 areattached to each other with a bonding layer 207 so that surfaces onwhich the layers to be separated are formed face each other, and thebonding layer 207 is cured (see FIG. 12C).

Note that the formation substrate 201 and the formation substrate 221are preferably attached to each other in a reduced-pressure atmosphere.

Although FIG. 12C illustrates the case where the separation layer 203and the separation layer 223 have different sizes, the separation layersmay have the same size as illustrated in FIG. 12D.

The bonding layer 207 is provided to overlap with the separation layer203, the layer 205, the layer 225, and the separation layer 223. Theedges of the bonding layer 207 are preferably positioned inside edges ofat least one of the separation layer 203 and the separation layer 223(the one intended to be separated first). Accordingly, strong adhesionbetween the formation substrate 201 and the formation substrate 221 canbe suppressed; thus, a decrease in yield of a subsequent separationprocess can be suppressed.

As the bonding layer 207, various curable adhesives such as a reactivecurable adhesive, a thermosetting adhesive, an anaerobic adhesive, and aphotocurable adhesive such as an ultraviolet curable adhesive can beused. Examples of these adhesives include an epoxy resin, an acrylicresin, a silicone resin, a phenol resin, a polyimide resin, an imideresin, a PVC resin, a PVB resin, and an EVA resin. A material with lowmoisture permeability, such as an epoxy resin, is particularlypreferred. For the adhesive, a material having fluidity low enough todispose the material only in a desired region is preferably used. Forexample, an adhesive sheet, a bonding sheet, or a sheet-like orfilm-like adhesive can be used, and an optical clear adhesive (OCA) filmcan be preferably used.

The adhesive may have adhesion before attachment or exhibit adhesionafter attachment by heating or light irradiation.

Furthermore, the resin may include a drying agent. For example, it ispossible to use a substance that adsorbs moisture by chemicaladsorption, such as oxide of an alkaline earth metal (e.g., calciumoxide or barium oxide), or a substance that adsorbs moisture by physicaladsorption, such as zeolite or silica gel. The drying agent ispreferably included, in which case it can suppress deterioration of thefunctional element due to entry of moisture in the air and can improvethe reliability of the device.

Next, a separation trigger is formed by laser light irradiation (seeFIGS. 13A and 13B).

Either the formation substrate 201 or the formation substrate 221 may beseparated first. In the case where the separation layers differ in size,a substrate over which a larger separation layer is formed may beseparated first or a substrate over which a smaller separation layer isformed may be separated first. In the case where an element such as asemiconductor element, a light-emitting element, or a display element isformed only over one of the substrates, the substrate where the elementis formed may be separated first or the other substrate may be separatedfirst. Here, an example in which the formation substrate 201 isseparated first is described.

A region where the cured bonding layer 207, the layer 205, and theseparation layer 203 overlap with each other is irradiated with laserlight (see an arrow P1 in FIG. 13A).

Part of the first layer is removed; thus, the separation trigger can beformed (see a region surrounded by a dashed line in FIG. 13B). At thistime, not only the first layer but also the separation layer 203, thebonding layer 207, or another layer included in the layer 205 may bepartly removed.

Laser light is preferably applied toward the substrate provided with theseparation layer that is desirably separated. When a region where theseparation layer 203 and the separation layer 223 overlap with eachother is irradiated with laser light, the formation substrate 201 andthe separation layer 203 can be selectively separated by cracking onlythe layer 205 between the layer 205 and the layer 225 (see the regionsurrounded by the dashed line in FIG. 13B. Here, an example in whichfilms of the layer 205 are partly removed is shown).

Then, the layer 205 and the formation substrate 201 are separated fromeach other from the separation trigger (see FIGS. 13C and 13D). Thus,the layer 205 can be transferred from the formation substrate 201 to theformation substrate 221.

For example, the layer 205 and the formation substrate 201 may beseparated from the separation trigger by mechanical force (e.g., aseparation process with a human hand or a gripper, or a separationprocess by rotation of a roller).

Alternatively, the formation substrate 201 and the layer 205 may beseparated by filling the interface between the separation layer 203 andthe layer 205 with a liquid such as water. A portion between theseparation layer 203 and the layer 205 absorbs a liquid throughcapillarity action, so that the separation layer 203 can be separatedeasily. Furthermore, an adverse effect of static electricity caused atseparation on the functional element included in the layer 205 (e.g.,damage to a semiconductor element from static electricity) can besuppressed.

Next, the exposed layer 205 is attached to a substrate 231 with abonding layer 233, and the bonding layer 233 is cured (see FIG. 14A).

Note that the layer 205 and the substrate 231 are preferably attached toeach other in a reduced-pressure atmosphere.

Subsequently, a separation trigger is formed by laser light irradiation(see FIGS. 14B and 14C).

A region where the cured bonding layer 233, the layer 225, and theseparation layer 223 overlap with each other is irradiated with laserlight (see an arrow P2 in FIG. 14B). Part of the first layer is removed;thus, the separation trigger can be formed (see a region surrounded by adashed line in FIG. 14C. Here, an example in which films of the layer225 are partly removed is shown). At this time, not only the first layerbut also the separation layer 223, the bonding layer 233, or anotherlayer included in the layer 225 may be partly removed.

Laser light is preferably applied toward the formation substrate 221provided with the separation layer 223.

Then, the layer 225 and the formation substrate 221 are separated fromeach other from the separation trigger (see FIG. 14D). Accordingly, thelayer 205 and the layer 225 can be transferred to the substrate 231.

In the above method for manufacturing the light-emitting device of oneembodiment of the present invention, separation is performed in such amanner that a separation trigger is formed by laser light irradiationafter a pair of formation substrates each provided with a separationlayer and a layer to be separated are attached to each other and thenthe separation layers and the layers to be separated are made in a statewhere separation is easily performed. Thus, the yield of the separationprocess can be improved.

In addition, separation is performed after the formation substrates eachprovided with the layer to be separated are attached to each other inadvance, and then a substrate where a device is intended to be formedcan be attached to the layers to be separated. Thus, to attach thelayers to be separated to each other, formation substrates having lowflexibility can be attached to each other; thus, alignment accuracy atthe time of attachment can be improved as compared to the case whereflexible substrates are attached to each other.

As illustrated in FIG. 15A, the edge of the layer 205 to be separated ispreferably positioned on the inner side of the edge of the separationlayer 203, in which case the yield of the separation process can beimproved. When there are a plurality of layers 205 to be separated, theseparation layer 203 may be provided for each layer 205 as illustratedin FIG. 15B or a plurality of layers 205 may be provided over oneseparation layer 203 as illustrated in FIG. 15C.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 4

In this embodiment, electronic appliances and lighting devices that canbe fabricated according to one embodiment of the present invention aredescribed with reference to FIGS. 16A to 16G and FIGS. 17A to 17I.

The input/output device of one embodiment of the present invention areflexible and thus are preferably used in a flexible electronic applianceand a flexible lighting device. According to one embodiment of thepresent invention, an electronic appliance and a lighting device thathave high reliability and high resistance to repeated bending can beachieved.

Examples of electronic appliances include a television set (alsoreferred to as television or television receiver), a monitor of acomputer or the like, a camera such as a digital camera and a digitalvideo camera, a digital photo frame, a mobile phone (also referred to asa cellular phone or mobile phone device), a portable game machine, aportable information terminal, an audio reproducing device, and a largegame machine such as a pachinko machine.

The input/output device of one embodiment of the present invention hasflexibility and therefore can be incorporated along a curvedinside/outside wall surface of a house or a building or a curvedinterior/exterior surface of a car.

An electronic appliance of one embodiment of the present invention mayinclude an input/output device and a secondary battery. In that case, itis preferred that the secondary battery is capable of being charged bynon-contact power transmission.

Examples of the secondary battery include a lithium ion secondarybattery such as a lithium polymer battery using a gel electrolyte(lithium ion polymer battery), a nickel-hydride battery, anickel-cadmium battery, an organic radical battery, a lead-acid battery,an air secondary battery, a nickel-zinc battery, and a silver-zincbattery.

An electronic appliance of one embodiment of the present invention mayinclude an input/output device and an antenna. Receiving a signal withthe antenna enables a display portion to display video, information, andthe like. When the electronic appliance includes a secondary battery,the antenna may be used for non-contact power transmission.

FIG. 16A illustrates an example of a mobile phone. A mobile phone 7400is provided with a display portion 7402 incorporated in a housing 7401,an operation button 7403, an external connection port 7404, a speaker7405, a microphone 7406, and the like. The mobile phone 7400 ismanufactured using the input/output device of one embodiment of thepresent invention for the display portion 7402. According to oneembodiment of the present invention, a highly reliable mobile phonehaving a curved display portion can be provided with a high yield.

When the display portion 7402 of the mobile phone 7400 in FIG. 16A istouched with a finger or the like, data can be input to the mobile phone7400. Operations such as making a call and inputting letters can beperformed by touch on the display portion 7402 with a finger or thelike.

With the operation button 7403, the power can be turned on and off.Furthermore, types of images displayed on the display portion 7402 canbe switched; for example, the image can be switched from a mail creationscreen to a main menu.

FIG. 16B illustrates an example of a wrist-watch-type portableinformation terminal. A portable information terminal 7100 includes ahousing 7101, a display portion 7102, a band 7103, a buckle 7104, anoperation button 7105, an input/output terminal 7106, and the like.

The portable information terminal 7100 is capable of executing a varietyof applications such as mobile phone calls, e-mailing, reading andediting texts, music reproduction, Internet communication, and acomputer game.

The display surface of the display portion 7102 is curved, and imagescan be displayed on the curved display surface. The display portion 7102includes a touch sensor, and operation can be performed by touching thescreen with a finger, a stylus, or the like. For example, an applicationcan be started by touching an icon 7107 displayed on the display portion7102.

With the operation button 7105, a variety of functions such as timesetting, power on/off, on/off control of wireless communication, settingand cancellation of manner mode, and setting and cancellation of powersaving mode can be performed. For example, the functions of theoperation button 7105 can be set freely by the operating systemincorporated in the portable information terminal 7100.

The portable information terminal 7100 can employ near fieldcommunication, which is a communication method based on an existingcommunication standard. In that case, for example, hands-free calling ispossible with mutual communication between the portable informationterminal 7100 and a headset capable of wireless communication.

Since the portable information terminal 7100 includes the input/outputterminal 7106, data can be directly transmitted to and received fromanother information appliance via a connector. Charging through theinput/output terminal 7106 is possible. Note that the charging operationmay be performed by wireless power feeding without using theinput/output terminal 7106.

The display portion 7102 of the portable information terminal 7100includes the input/output device of one embodiment of the presentinvention. According to one embodiment of the present invention, ahighly reliable portable information terminal having a curved displayportion can be provided with a high yield.

FIGS. 16C to 16E illustrate examples of lighting devices. Lightingdevices 7200, 7210, and 7220 each include a stage 7201 provided with anoperation switch 7203 and a light-emitting portion supported by thestage 7201.

The lighting device 7200 illustrated in FIG. 16C includes alight-emitting portion 7202 with a wave-shaped light-emitting surfaceand thus is a good-design lighting device.

A light-emitting portion 7212 included in the lighting device 7210 inFIG. 16D has two convex-curved light-emitting portions symmetricallyplaced. Thus, light radiates from the lighting device 7210 in alldirections.

The lighting device 7220 illustrated in FIG. 16E includes aconcave-curved light-emitting portion 7222. This is suitable forilluminating a specific range because light emitted from thelight-emitting portion 7222 is collected at the front of the lightingdevice 7220.

The light-emitting portion included in each of the lighting devices7200, 7210, and 7220 is flexible; accordingly, the light-emittingportion may be fixed on a plastic member, a movable frame, or the likeso that a light-emitting surface of the light-emitting portion can bebent freely depending on the intended use.

Although the lighting devices in which the light-emitting portion issupported by the stage are described as examples, a housing providedwith a light-emitting portion can be fixed on a ceiling or suspendedfrom a ceiling. Since the light-emitting surface can be curved, thelight-emitting surface can be bent concavely so that a particular regionis brightly illuminated, or bent convexly so that the whole room isbrightly illuminated.

Here, each of the light-emitting portions includes the input/outputdevice of one embodiment of the present invention. According to oneembodiment of the present invention, a highly reliable lighting devicehaving a curved light-emitting portion can be provided with a highyield.

FIG. 16F illustrates an example of a portable input/output device. Aninput/output device 7300 includes a housing 7301, a display portion7302, operation buttons 7303, a display portion pull 7304, and a controlportion 7305.

The input/output device 7300 includes a rolled flexible display portion7302 in the cylindrical housing 7301.

The input/output device 7300 can receive a video signal with the controlportion 7305 and display the received video on the display portion 7302.The control portion 7305 includes a battery. Moreover, the controlportion 7305 may include a terminal portion for connecting a connectorso that a video signal or power can be directly supplied from theoutside through a wire.

By pressing the operation buttons 7303, power on/off, switching ofdisplayed video, and the like can be performed.

FIG. 16G illustrates the input/output device 7300 in a state where thedisplay portion 7302 is pulled out with the display portion pull 7304.Video can be displayed on the display portion 7302 in this state. Theoperation buttons 7303 on the surface of the housing 7301 allowone-handed operation. The operation buttons 7303 are provided not in thecenter of the housing 7301 but on one side of the housing 7301 asillustrated in FIG. 16F, which makes one-handed operation easy.

A reinforcement frame may be provided for a side portion of the displayportion 7302 so that the display portion 7302 has a flat display surfacewhen pulled out.

Note that in addition to this structure, the housing may be providedwith a speaker so that sound is output with an audio signal receivedtogether with a video signal.

The display portion 7302 includes the input/output device of oneembodiment of the present invention. According to one embodiment of thepresent invention, a lightweight and highly reliable input/output devicecan be provided with a high yield.

FIGS. 17A to 17C illustrate a foldable portable information terminal310. FIG. 17A illustrates the portable information terminal 310 that isopened. FIG. 17B illustrates the portable information terminal 310 thatis being opened or being folded. FIG. 17C illustrates the portableinformation terminal 310 that is folded. The portable informationterminal 310 is highly portable when folded, and is highly browsablewhen opened because of a seamless large display area.

A display panel 316 is supported by three housings 315 joined togetherby hinges 313. By folding the portable information terminal 310 at aconnection portion between two housings 315 with the hinges 313, theportable information terminal 310 can be reversibly changed in shapefrom an opened state to a folded state. The input/output device of oneembodiment of the present invention can be used for the display panel316. For example, it is possible to use a light-emitting device or aninput/output device that can be bent with a radius of curvature of 1 mmor more and 150 mm or less.

In one embodiment of the present invention, a sensor that senses whetherthe input/output device is folded or opened and supplies sensinginformation may be provided. When obtaining information indicating thatthe input/output device is folded, a control portion of the input/outputdevice may stop a folded portion (or a portion that is folded and cannotbe seen by a user) from operating, specifically performing display orsensing by a touch sensor.

Similarly, the control portion of the input/output device may makedisplay and sensing by a touch sensor restart when obtaining informationindicating that the input/output device is opened.

FIGS. 17D and 17E illustrate a foldable portable information terminal320. FIG. 17D illustrates the portable information terminal 320 that isfolded so that a display portion 322 is on the outside. FIG. 17Eillustrates the portable information terminal 320 that is folded so thatthe display portion 322 is on the inside. When the portable informationterminal 320 is not used, the portable information terminal 320 isfolded so, that a non-display portion 325 faces the outside, whereby thedisplay portion 322 can be prevented from being contaminated or damaged.The light-emitting device or the input/output device of one embodimentof the present invention can be used for the display portion 322.

FIG. 17F is a perspective view illustrating the external shape of aportable information terminal 330. FIG. 17G is a top view of theportable information terminal 330. FIG. 17H is a perspective viewillustrating the external shape of a portable information terminal 340.

The portable information terminals 330 and 340 function as one or moreof a telephone set, an electronic notebook, and an information browsingsystem, for example.

Specifically, each of the portable information terminals 330 and 340 canbe used as a smartphone.

The portable information terminals 330 and 340 can display letters andimage data on their plurality of surfaces. For example, three operationbuttons 339 can be displayed on one surface (see FIGS. 17F and 17H).Moreover, information 337 indicated by dashed rectangles can bedisplayed on another surface (see FIGS. 17G and 17H). Examples of theinformation 337 include notification of a social networking service(SNS) message, display indicating reception of an email or an incomingcall, the title or sender of an email or the like, the date, the time,remaining battery, and the reception strength of an antenna.Alternatively, the operation button 339, an icon, or the like may bedisplayed in place of the information 337. Although FIGS. 17F and 17Gshow the example in which the information 337 is displayed at the top,one embodiment of the present invention is not limited to this example.For instance, the information 337 may be displayed on the side as in theportable information terminal 340 in FIG. 17H.

For example, a user of the portable information terminal 330 can see thedisplay (here, the information 337) with the portable informationterminal 330 put in a breast pocket.

Specifically, a caller's phone number, name, or the like of an incomingcall is displayed in a position that can be seen from above the portableinformation terminal 330. Thus, the user can see the display withouttaking out the portable information terminal 330 from the pocket anddecide whether to answer the call.

The input/output device of one embodiment of the present invention canbe used for a display portion 333 included in a housing 335 of theportable information terminal 330 and a housing 336 of the portableinformation terminal 340. According to one embodiment of the presentinvention, a highly reliable portable information terminal having acurved display portion can be provided with a high yield.

As in a portable information terminal 345 illustrated in FIG. 17I,information may be displayed on at least three surfaces. Here, as anexample, information 355, information 356, and information 357 aredisplayed on different surfaces.

The input/output device of one embodiment of the present invention canbe used for a display portion 358 included in a housing 354 of theportable information terminal 345. According to one embodiment of thepresent invention, a highly reliable portable information terminalhaving a curved display portion can be provided with a high yield.

This embodiment can be combined with any other embodiment asappropriate.

This application is based on Japanese Patent Application serial No.2014-095116 filed with the Japan Patent Office on May 2, 2014, theentire contents of which are hereby incorporated by reference.

What is claimed is:
 1. A display device comprising: a first flexiblesubstrate; a first bonding layer over the first flexible substrate; afirst insulating layer over the first bonding layer; a first transistorover the first insulating layer; a first conductive layer over the firstinsulating layer; a light-emitting element electrically connected to thefirst transistor, the light-emitting element comprising an EL layerbetween a first electrode and a second electrode; a second bonding layerover the light-emitting element; a sensing element and a secondtransistor that are over the second bonding layer and electricallyconnected to each other; a second insulating layer over the sensingelement and the second transistor; a third bonding layer over the secondinsulating layer; a second flexible substrate over the third bondinglayer; a first flexible printed circuit over the first flexiblesubstrate; and a second flexible printed circuit electrically connectedto the sensing element, wherein the first flexible printed circuit iselectrically connected to the first conductive layer, and wherein atleast part of an edge of the first bonding layer is positioned outsidean edge of the first flexible substrate.
 2. The display device accordingto claim 1, wherein at least one of the first transistor and the secondtransistor comprises an oxide semiconductor in a channel formationregion, and wherein the oxide semiconductor comprises indium and zinc.3. The display device according to claim 1, wherein a thickness of thefirst bonding layer is greater than or equal to 50 nm and less than orequal to 3 □m.
 4. The display device according to claim 1, wherein thefirst flexible printed circuit is electrically connected to the firstconductive layer through an opening in the second insulating layer andthe second bonding layer.
 5. The display device according to claim 1,wherein a thickness of the second bonding layer is greater than or equalto 50 nm and less than or equal to 3 □m.
 6. The display device accordingto claim 1, wherein at least part of an edge of the third bonding layeris positioned outside an edge of the second flexible substrate.
 7. Thedisplay device according to claim 1, further comprising a color filterbetween the light-emitting element and the sensing element.
 8. Thedisplay device according to claim 1, further comprising a light-blockinglayer, wherein the light-blocking layer and the second transistoroverlap each other.
 9. An electronic appliance comprising: the displaydevice according to claim 1; and at least one of a battery, an antenna,a speaker, and an operating key.
 10. A display device comprising: afirst flexible substrate; a first bonding layer over the first flexiblesubstrate; a first insulating layer over the first bonding layer; afirst transistor over the first insulating layer; a first conductivelayer over the first insulating layer; a light-emitting elementelectrically connected to the first transistor, the light-emittingelement comprising an EL layer between a first electrode and a secondelectrode; a second bonding layer over the light-emitting element; asensing element and a second transistor that are over the second bondinglayer and electrically connected to each other; a second insulatinglayer over the sensing element and the second transistor; a thirdbonding layer over the second insulating layer; a second flexiblesubstrate over the third bonding layer; a first flexible printed circuitover the first flexible substrate; and a second flexible printed circuitelectrically connected to the sensing element through an opening in thefirst insulating layer and the second bonding layer., wherein the firstflexible printed circuit is electrically connected to the firstconductive layer, and wherein at least part of an edge of the firstbonding layer is positioned outside an edge of the first flexiblesubstrate.
 11. The display device according to claim 10, wherein atleast one of the first transistor and the second transistor comprises anoxide semiconductor in a channel formation region, and wherein the oxidesemiconductor comprises indium and zinc.
 12. The display deviceaccording to claim 10, wherein a thickness of the first bonding layer isgreater than or equal to 50 nm and less than or equal to 3 □m.
 13. Thedisplay device according to claim 10, wherein the first flexible printedcircuit is electrically connected to the first conductive layer throughan opening in the second insulating layer and the second bonding layer.14. The display device according to claim 10, wherein a thickness of thesecond bonding layer is greater than or equal to 50 nm and less than orequal to 3 □m.
 15. The display device according to claim 10, wherein atleast part of an edge of the third bonding layer is positioned outsidean edge of the second flexible substrate.
 16. The display deviceaccording to claim 10, further comprising a color filter between thelight-emitting element and the sensing element.
 17. The display deviceaccording to claim 10, further comprising a light-blocking layer,wherein the light-blocking layer and the second transistor overlap eachother.
 18. An electronic appliance comprising: the display deviceaccording to claim 10; and at least one of a battery, an antenna, aspeaker, and an operating key.